Automatically Verifying Concurrent Queue Algorithms

Concurrent FIFO queues are a common component of concurrent systems. Using a single shared lock to prevent concurrent manipulations of queue contents reduces system concurrency. Therefore, many algorithms were suggested to increase concurrency while maintaining the correctness of queue manipulations. This paper shows how to automatically verify partial correctness of concurrent FIFO queue algorithms using existing abstract interpretation techniques. In particular, we verify all the safety properties originally specified for two concurrent queue algorithms without imposing an a priori bound on the number of allocated objects and threads.     

Impulse-based control of joints and muscles

We propose a novel approach to proportional derivative (PD) control exploiting the fact that these equations can be solved analytically for a single degree of freedom. The analytic solution indicates what the PD controller would accomplish in isolation without interference from neighboring joints, gravity and external forces, outboard limbs, etc. Our approach to time integration includes an inverse dynamics formulation that automatically incorporates global feedback so that the per joint predictions are achieved. This effectively decouples stiffness from control so that we obtain the desired target regardless of the stiffness of the joint, which merely determines when we get there. We start with simple examples to illustrate our method, and then move on to more complex examples including PD control of line segment muscle actuators.     

Crowdsourcing privacy preferences in context-aware applications

Developers of context-aware applications are faced with a tough challenge: powerful privacy controls are essential to maintain user trust, but they are also hard to use and not adequate in all situations. To address this tradeoff, we present Super-Ego, a crowdsourcing framework for privacy management of location information in ubiquitous environment. We study how crowdsourcing can be used to predict the user’s privacy preferences for different location on the basis of the general user population. The crowdsourcing methods are evaluated in a 2-week user study in which we tracked the locations of 30 subjects and asked them to provide privacy preferences for the locations they had visited. Our results show that by employing simple methods for semantic analysis of locations and by profiling the user’s privacy inclination, our methods can accurately predict the privacy preferences for 80 % of the user’s locations. By employing semi-automatic decision strategies, which ask the user to decide regarding the privacy of some of the locations, the accuracy rate raises to 90 %.     

A comparative study of electrodes comprising nanometric and submicron particles of LiNi0.50Mn0.50O2, LiNi0.33Mn0.33Co0.33O2, and LiNi0.40Mn0.40Co0.20O2 layered compounds

In this paper we compare the behavior of LiNi_0.5Mn_0.5O₂, LiNi_0.33Mn_0.33Co_0.33O₂ (NMC) and LiNi_0.4Mn_0.4Co_0.2O₂ as cathode materials for advanced rechargeable Li-ion batteries. These materials were prepared by a self-combustion reaction (SCR) from the metal nitrates and sucrose, followed by calcination at elevated temperatures. The temperature and duration of calcination enabled the adjustment of the average particle size and size distribution. It was established that the annealing temperature (700–900 °C) of the as-prepared oxides influences strongly the crystallite and particle size, the morphology of the material, and the electrochemical performance of electrodes in Li-cells. Capacities up to 190, 180 and 170 mAh g⁻¹ could be obtained with Li[NiMn]O₂, LiNi_0.4Mn_0.4Co_0.2O₂ and LiNi_0.33Mn_0.33Co_0.33O₂, respectively. In terms of rate capability, the order of these electrodes is NMC < LiNi_0.4Mn_0.4Co_0.2O₂ ? Li[NiMn]O₂. Many hundreds of cycles at full DOD could be obtained with Li[NiMn]O₂ and NMC electrodes in Li-cells, at room temperature. All of these materials develop a unique surface chemistry that leads to their passivation and stabilization in standard electrolyte solutions (alkyl carbonates/LiPF₆). The surface chemistry was studied by FTIR, XPS and Raman spectroscopy and is discussed herein.     

A different approach for predicting H(2)S((g)) emission rates in gravity sewers

All detrimental phenomena (mal odors, metal corrosion, concrete disintegration, health hazard) associated with hydrogen sulfide in gravity sewers depend on the rate of H(2)S emission from the aqueous phase to the gas phase of the pipe. In this paper a different approach for predicting H(2)S((g)) emission rates from gravity sewers is presented, using concepts adapted from mixing theory. The mean velocity gradient (G=gamma SV/micro; S is the slope, V the mean velocity), representing mixing conditions in gravity flow, was used to quantify the rate of H(2)S((g)) emission in part-full gravity sewers. Based on this approach an emission equation was developed. The equation was verified and calibrated by performing 20 experiments in a 27-m gravity-flow experimental-sewer (D=0.16 m) at various hydraulic conditions. Results indicate a clear dependency of the sulfide stripping-rate on G(1) (R(2)=0.94) with the following overall emission equation: where S(T) is the total sulfide concentration in the aqueous phase, mg/L; w the flow surface width, m; A(cs) the cross-sectional area, m(2); T the temperature, degrees C; K(H) the Henry's constant, molL(-1)atm(-1); and P(pH2S) the partial pressure of H(2)S((g)) in the sewer atmosphere, atm.     

Portable parallel FFT for MIMD multiprocessors

A portable parallelization of the Cooley–Tukey FFT algorithm for MIMD multiprocessors is presented. The implementation uses the virtual machine for multiprocessors (VMMP) and PVM portable software packages. Since VMMP provides the same set of services on all target machines, a single version of the parallel FFT code was used for shared memory (25-processor Sequent Symmetry), shared bus (MOS-running distributed UNIX) and distributed memory multiprocessor (transputer network and 64-processor IBM SP2). It is accompanied with detailed performance analysis of the implementations. The algorithm achieved high efficiencies on all target machines. The analysis indicates that most overheads are caused by the target architecture and not by VMMP or PVM inefficiencies. The portability analysis of the FFT provides several important insights. On the message passing architecture, the parallel FFT algorithm can obtain linearly increasing speedup with respect to the number of processors with only a moderate increase in the problem size. The parallel FFT can be executed by any number of processors, but generally the number of processors is much less than the length of the input data. The results indicate that the parallel FFT is portable: it achieves very good speedups on either a shared memory multiprocessor with high memory bandwidth or on a message passing multiprocessor without any change in the programs. © 1998 John Wiley & Sons, Ltd.     

Jellyfish‐Based Smart Wound Dressing Devices Containing In Situ Synthesized Antibacterial Nanoparticles

Although the negative consequences of the global phenomenon of jellyfish (JF) swarms are well recognized, the use of their biomass for practical applications is mostly limited to a niche in the Asian food industry. This fact is quite surprising since JF's biomass comprises useful biomaterials such as Q‐mucin glycoprotein and collagen. In this work, the JF biomass, collected from two different species, is used to prepare electrospun scaffolds composed of nanometric “core–shell”‐type fibers, in which adjustment of the electrospinning process parameters can easily control their mechanical, morphological, and chemical properties. This nonwoven scaffold shows excellent biocompatibility and biodegradability, indicating suitability for biomedical research contexts. Performed cell proliferation assays show that the scaffold could support the growth of cardiac cells, fitting the requirement of tissue engineering. Additional incorporation of in situ‐generated silver nanoparticles in these nanofibers produced mats with potent antibacterial properties. Preclinical trials with the resulted mats on porcine wound healing models exhibit fast and complete healing of wounds.     

Apportioned margin approach for cost sensitive large margin classifiers

We consider the problem of cost sensitive multiclass classification, where we would like to increase the sensitivity of an important class at the expense of a less important one. We adopt an apportioned margin framework to address this problem, which enables an efficient margin shift between classes that share the same boundary. The decision boundary between all pairs of classes divides the margin between them in accordance with a given prioritization vector, which yields a tighter error bound for the important classes while also reducing the overall out-of-sample error. In addition to demonstrating an efficient implementation of our framework, we derive generalization bounds, demonstrate Fisher consistency, adapt the framework to Mercer’s kernel and to neural networks, and report promising empirical results on all accounts.

     

Suitability of Raman Spectroscopy for Assessing Anisotropic Strain in Thin Films of Doped Ceria

A protocol for characterizing relaxation of anisotropic strain in thin films of 10 mol% Eu‐ or Sm‐doped ceria is described. The method is based on comparison of Raman spectra and X‐ray diffraction patterns from substrate‐supported films, displaying in‐plane compressive strain (initial state), with analogous data from 2 mm diameter self‐supported films (i.e., membranes), prepared by partial substrate removal (final state). These membranes are found to be relaxed, i.e., approximately unstrained, but with increased unit cell volume. The effective (i.e., 2‐state) Grüneisen parameter of the F_2g Raman active mode for these films is calculated to be 0.4 ± 0.1, which is ≈30% of the literature value for the corresponding ceramics under isostatic pressure. On this basis, it is found that the observed red‐shift of the F_2g mode frequency following isothermal strain relaxation of the doped ceria thin films cannot be determined solely by the increase in average unit cell volume. The study presented here may shed light on the suitability of Raman spectroscopy as a technique for characterizing strain in lanthanide‐doped ceria thin films.     

Communication and Learning: The Bilateral Information Transmission in the Cobweb Model

Computational Economics - Communication is a natural activity to gain information and exchange ideas for making proper economic decisions. The mechanism of social interaction remains inadequately...