Randomized function evaluation on a ring

LetR be a unidirectional asynchronous ring ofn identical processors each with a single input bit. Letf be any cyclic nonconstant function ofn boolean variables. Moran and Warmuth (1986) prove that anydeterministic algorithm that evaluatesf onR has communication complexity (n logn) bits. They also construct a family of cyclic nonconstant boolean functions that can be evaluated inO(n logn) bits by a deterministic algorithm.This contrasts with the following new results:

A resilience optimization approach for workforce-inventory control dynamics under uncertainty

The presence of uncertainties in manufacturing systems and supply chains can cause undesirable behavior. Failure to account for these in the design phase can further impair the capability of systems to respond to changes effectively. In this work, we consider a dynamic workforce-inventory control problem wherein inventory planning, production releases, and workforce hiring decisions need to be made. The objective is to develop planning rules to achieve important requirements related to dynamic transient behavior when system parameters are imprecisely known. To this end, we propose a resilience optimization model for the problem and develop a novel local search procedure that combines the strengths of recent developments in robust optimization technology and small signal stability analysis of dynamic systems. A numerical case study of the problem demonstrates significant improvements of the proposed solution in controlling fluctuations and high variability found in the system’s inventory, work-in-process, and workforce levels. Overall, the proposed model is shown to be computationally efficient and effective in hedging against model uncertainties.     

A comprehensive study on co2-interphase mass transfer in vertical cocurrent and countercurrent gas-liquid flow

Cocurrent and countercurrent absorption and desorption of CO₂ in water was investigated in tall bubble columns (length 440 and 720 cm, diameter 15 and 20 cm, respectively). Operating conditions were applied which provided for high interphase mass transfer rates. Under these circumstances the relative gas holdup varies considerably with axial position whereas the mean bubble diameter measured at two points was found to be approximately constant. The measured data permit the calculation of local values of interfacial areas, superficial gas velocities, and frequency factors for bubble coalescence and break up. A dispersion model which takes into account the hydrostatic head and a variable gas velocity was applied to describe the measured concentration profiles in both phases. If increased mass transfer coefficients at the column bottom and measured local values of the hold up were used a striking agreement between experimental and predicted profiles could be obtained. The findings lead to a more sophisticated picture of the complex behaviour of gas-liquid dispersions at high interphase mass transfer rates.     

High clay content nanocomposite hydrogels with surprising mechanical strength and interesting deswelling kinetics

A series of high hectorite content nanocomposite Poly (N-isopropylacrylamide), (PNIPAAm), hydrogels have been successfully synthesized by choosing a special kind of hectorite (Laponite XLS) modified by tetrasodium pyrophosphate. It was found that these hydrogels show surprising mechanical properties (i.e. tensile strength: 1 MPa, elongation at break: 1400%) and complicated deswelling behavior, which are due to the high clay content of the hydrogels and ionic dispersant contained in Laponite XLS, respectively.     

Path‐space Motion Estimation and Decomposition for Robust Animation Filtering

Renderings of animation sequences with physics‐based Monte Carlo light transport simulations are exceedingly costly to generate frame‐by‐frame, yet much of this computation is highly redundant due to the strong coherence in space, time and among samples. A promising approach pursued in prior work entails subsampling the sequence in space, time, and number of samples, followed by image‐based spatio‐temporal upsampling and denoising. These methods can provide significant performance gains, though major issues remain: firstly, in a multiple scattering simulation, the final pixel color is the composite of many different light transport phenomena, and this conflicting information causes artifacts in image‐based methods. Secondly, motion vectors are needed to establish correspondence between the pixels in different frames, but it is unclear how to obtain them for most kinds of light paths (e.g. an object seen through a curved glass panel). To reduce these ambiguities, we propose a general decomposition framework, where the final pixel color is separated into components corresponding to disjoint subsets of the space of light paths. Each component is accompanied by motion vectors and other auxiliary features such as reflectance and surface normals. The motion vectors of specular paths are computed using a temporal extension of manifold exploration and the remaining components use a specialized variant of optical flow. Our experiments show that this decomposition leads to significant improvements in three image‐based applications: denoising, spatial upsampling, and temporal interpolation.     

Analysis of Distance Collaboration Modalities: Alternatives to Meeting Face-to-Face

Physical and temporal boundaries are rapidly diminishing in an age of swiftly advancing information communication technologies. Today’s technologically sophisticated business and organizational environments offer a number of distance collaboration modalities (DSMs) that can facilitate efficient and cost-effective meetings that have traditionally required face-to-face meeting venues. Selection of the DCMs that maximize meeting effectiveness is significantly challenging given the wide diversity of available options. Theory and empirical data can be useful as a guide in the selection of the most appropriate DCMs to maximize organizational productivity and success. This article reviews the literature on the behavioral and technical affordances and limitations of the various DCMs. It also provides a theoretical model based on media synchronicity theory to help guide selection of effective DCMs. This theoretical framework emphasizes the primacy of media alignment with core communication processes as well as social and interpersonal factors that influence meeting effectiveness.     

Planar Segment Based Three‐dimensional Point Cloud Registration in Outdoor Environments

We present an odometry‐free three‐dimensional (3D) point cloud registration strategy for outdoor environments based on area attributed planar patches. The approach is split into three steps. The first step is to segment each point cloud into planar segments, utilizing a cached‐octree region growing algorithm, which does not require the 2.5D image‐like structure of organized point clouds. The second step is to calculate the area of each segment based on small local faces inspired by the idea of surface integrals. The third step is to find segment correspondences between overlapping point clouds using a search algorithm, and compute the transformation from determined correspondences. The transformation is searched globally so as to maximize a spherical correlation‐like metric by enumerating solutions derived from potential segment correspondences. The novelty of this step is that only the area and plane parameters of each segment are employed, and no prior pose estimation from other sensors is required. Four datasets have been used to evaluate the proposed approach, three of which are publicly available and one that stems from our custom‐built platform. Based on these datasets, the following evaluations have been done: segmentation speed benchmarking, segment area calculation accuracy and speed benchmarking, processing data acquired by scanners with different fields of view, comparison with the iterative closest point algorithm, robustness with respect to occlusions and partial observations, and registration accuracy compared to ground truth. Experimental results confirm that the approach offers an alternative to state‐of‐the‐art algorithms in plane‐rich environments.