Review of scientific technology-based solutions for vehicular pollution control

Clean Technologies and Environmental Policy - Numerous management strategies are implemented for the improvement in urban air quality worldwide, including control at tailpipe emissions. Control at...     

Deployable Structures Based on Buckling of Curved Beams Upon a Rotational Input

Inspired by the recent success of buckling-induced reconfigurable structures, a new class of deployable systems that harness buckling of curved beams upon a rotational input is proposed. First, experimental and numerical methods are combined to investigate the influence of the beam's geometric parameters on its non-linear response. Then, it is shown that a wide range of deployable architectures can be realized by combining curved beams. Finally, the proposed principles are used to build deployable furniture such as tables and lamp shades that are flat/compact for transportation and storage, require simple or no assembly, and can be expanded by applying a simple rotational input.     

Timbre features with MEDIAN values for compensating intra-speaker variability in speaker identification of whispering sound

International Journal of Speech Technology - Because voiced phonations are absent in the whisper, distinguishing among the speakers with whispered voice is a difficult task. The selection...     

A new modelling and identification scheme for time-delay systems with experimental investigation: a relay feedback approach

In this paper, the conventional relay feedback test has been modified for modelling and identification of a class of real-time dynamical systems in terms of linear transfer function models with time-delay. An ideal relay and unknown systems are connected through a negative feedback loop to bring the sustained oscillatory output around the non-zero setpoint. Thereafter, the obtained limit cycle information is substituted in the derived mathematical equations for accurate identification of unknown plants in terms of overdamped, underdamped, critically damped second-order plus dead time and stable first-order plus dead time transfer function models. Typical examples from the literature are included for the validation of the proposed identification scheme through computer simulations. Subsequently, the comparisons between estimated model and true system are drawn through integral absolute error criterion and frequency response plots. Finally, the obtained output responses through simulations are verified experimentally on real-time liquid level control system using Yokogawa Distributed Control System CENTUM CS3000 set up.     

Low-temperature machining in a fully submerged cryogenic environment

The role of an immersive cryogenic environment in affecting material response in machining was explored using dynamometry, calorimetry, electron microscopy, and microindentation. Effects of tool rake angle on energy dissipation, stored energy of cold work, deformed microstructure, and hardening were evaluated for machining under a fully submerged cryogenic cutting environment and a dry cutting environment. Sustained immersion of the cutting zone in liquid nitrogen resulted in greater energy dissipation and hardening in the work and machined subsurface. This increased hardening at low temperature was directly linked to greater microstructure refinement and a lower fraction of dissipated energy stored in the form of added defects and grain boundaries. Various microstructure types with domain sizes from microscale to nanoscale were developed in the machined chips, depending on the rake angle and temperature used.     

SSPH basis functions for meshless methods, and comparison of solutions with strong and weak formulations

We propose a new and simple technique called the Symmetric Smoothed Particle Hydrodynamics (SSPH) method to construct basis functions for meshless methods that use only locations of particles. These basis functions are found to be similar to those in the Finite Element Method (FEM) except that the basis for the derivatives of a function need not be obtained by differentiating those for the function. Of course, the basis for the derivatives of a function can be obtained by differentiating the basis for the function as in the FEM and meshless methods. These basis functions are used to numerically solve two plane stress/strain elasto-static problems by using either the collocation method or a weak formulation of the problem defined over a subregion of the region occupied by the body; the latter is usually called the Meshless Local Petrov–Galerkin (MLPG) method. For the two boundary-value problems studied, it is found that the weak formulation in which the basis for the first order derivatives of the trial solution are derived directly in the SSPH method (i.e., not obtained by differentiating the basis function for the trial solution) gives the least value of the L²-error norm in the displacements while the collocation method employing the strong formulation of the boundary-value problem has the largest value of the L²-error norm. The numerical solution using the weak formulation requires more CPU time than the solution with the strong formulation of the problem. We have also computed the L²-error norm of displacements by varying the number of particles, the number of Gauss points used to numerically evaluate domain integrals appearing in the weak formulation of the problem, the radius of the compact support of the kernel function used to generate the SSPH basis, the order of complete monomials employed for constructing the SSPH basis, and boundary conditions used at a point on a corner of the rectangular problem domain. It is recommended that for solving two-dimensional elasto-static problems, the MLPG formulation in which derivatives of the trial solution are found without differentiating the SSPH basis function be adopted.     

Free and Forced Vibrations of a Segmented Bar by a Meshless Local Petrov–Galerkin (MLPG) Formulation

We use the meshless local Bubnov–Galerkin (MLPG6) formulation to analyze free and forced vibrations of a segmented bar. Three different techniques are employed to satisfy the continuity of the axial stress at the interface between two materials: Lagrange multipliers, jump functions, and modified moving least square basis functions with discontinuous derivatives. The essential boundary conditions are satisfied in all cases by the method of Lagrange multipliers. The related mixed semidiscrete formulations are shown to be stable, and optimal in the sense that the ellipticity and the inf-sup (Babuška-Brezzi) conditions are satisfied. Numerical results obtained for a bimaterial bar are compared with those from the analytical, and the finite element methods. The monotonic convergence of first two natural frequencies, first three mode shapes, and a static solution in the L ², and H ¹ norms is shown. The relative error in the numerical solution for a transient problem is also very small.     

Topological analysis of catalytic reaction networks: Methanol decomposition on Pt(111)

We describe our new reaction route (RR) graph approach as a powerful new tool for topological mechanistic and kinetic analysis of catalytic reaction networks, illustrated here with the help of methanol decomposition on Pt(111). In this approach a graph-theoretic network of molecular reaction steps is first constructed for the overall reaction (OR), on which each mechanistic step is represented by a directed branch interconnected at nodes, such that all conceivable reaction pathways can then be traced on it simply as walks or paths. Further, the network is consistent with the basic laws of flow graphs, so that it is suitable for a quantitative analysis. In fact, a direct analogy can be made to an equivalent wiring diagram, which allows tools of electric circuit analysis, namely, Kirchhoff's laws of current (rate) and potential (affinity), to be directly utilized for a rigorous flux analysis of the network. As a result, the dominant pathways as well as the rate-limiting steps (RLS) become transparent. This furthermore facilitates network pruning to retain only the essential steps and pathways. The RR graph approach when combined with ab initio kinetics, thus, provides a rigorous new framework for analyzing the mechanism and kinetics of catalytic reactions. It is, thus, found that methanol decomposition proceeds exclusively via the initial CH dehydrogenation step rather than through OH bond activation.     

The sexual harassment of men: Evidence for a broader theory of sexual harassment and sex discrimination.

The article imposes a social science framework on a law-based theory of sexual harassment forwarded by Katherine Franke (1997), which sought to address shortcomings of extant theory and to account for atypical forms of sexual harassment, notably male same-sex sexual harassment (SSSH). Sex-role spillover theory, sexual harassment climate theory, and Person × Situation theory are discussed with regard to their ability to account for SSSH. Preliminary postulates of this framework are tested with data from the 1995 Department of Defense sexual harassment survey of the U.S. military (J. E. Edwards, T. W. Elig, D. L. Edwards, & R. A. Riemer (1997). The results suggest that SSSH occurs because targeted men do not fit their offenders' gender-role stereotype of heterosexual hypermasculinity. Legal and workplace implications are discussed in an effort to expand existing theories and policies regarding sexual harassment to this more encompassing view. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Increased thermal tolerance in Cronobacter sakazakii strains in reconstituted milk powder due to cross protection by physiological stresses

Cronobacter sakazakii (C. sakazakii) is an opportunistic, neonatal, and food borne pathogen primarily associated with the contamination of powdered infant formula (PIF). The pathogen is reported to overcome the food safety barriers such as increased acidity, heat treatment, and so on. This study evaluates the thermal tolerance of C. sakazakii strains independently at 52, 55, and 58°C in reconstituted PIF after exposure to physiological stresses: refrigeration (4°C for 24 hr), starvation (37°C for 48 hr), and desiccation (25°C for 4 days). The Log₁₀ CFU/ml and D-values indicated that survival rate of all the strains decreased significantly (p < .05) after desiccation as compared to those of the control condition (without stress exposure). However, cold stress increased the thermal tolerance of all strains at all temperatures (52, 55, and 58°C) as indicated by increased D-values. Among the tested strains, C. sakazakii strain N15 was found to be the most resistant to thermal treatment after each stress exposure as depicted by principal component analysis (PCA). No apparent correlation between thermal tolerance and starvation stress was observed. The findings indicate that prior exposure to stress conditions may induce cross protection to thermal treatment in C. sakazakii.