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A model of dynamic deformation and fracture of composite materials is developed. This model accounts for the significant nonlinearity of shock loading diagrams with hardening, which depends on strain rate. An approach is used in which the dependence of ultimate strength on damage parameters and their variation rate is introduced in the form of constitutive relations. The proposed relations are similar to those of the Johnson—Cook model, but stresses are expressed via damage parameters and their variation rate rather than in terms of plastic deformations and the variation rate of plastic deformations. On the basis of the developed model, the impact fracture of a tubular profile made of a composite material based on carbon fiber and a polymer binder are numerically simulated. The influence of the orientation of unidirectional layers of a composite on specific absorption energy is investigated. [ABSTRACT FROM AUTHOR]

In this paper, asymmetric equations for an elliptical boundary layer in the vicinity of the conditional front of Rayleigh surface waves, which occurs in shells of revolution under shock end impacts of normal type are constructed. The technique of asymptotic derivation of these equations, based on the use of the symbolic Lurie method and the introduction of special coordinates that distinguish a small frontal zone required to reduce the original problem to an equivalent problem for an infinite shell by isolating a particular solution. The considered boundary layer complements the full description of the considered type of stress-strain state (SSS) in all sections of the phase plane. It also uses a quasi-static boundary layer of the Saint-Venant type in a small vicinity of the butt end, a parabolic boundary layer according to the two-dimensional Kirchhoff–Love theory, a quasi-plane short-wave component, and a hyperbolic boundary layer in a small neighborhood of the shear wave front. In conclusion, an example of constructing an elliptical boundary layer under shock action on the butt end of a cylindrical shell is considered. [ABSTRACT FROM AUTHOR]

Since anaerobic wastewater treatment is a nonlinear and complex biochemical process, reasonable monitoring and control are needed to keep it operating stably and efficiently. In this paper, a least-square support-vector machine (LS-SVM) was employed to construct models for the prediction of effluent chemical oxygen demand (COD) in an anaerobic wastewater treatment system. The result revealed that the performance of the steady-state model based on LS-SVM for predicting effluent COD was acceptable, with the maximum relative error (RE) of 11.45%, the mean average percentage error (MAPE) of 0.79% and the root mean square error (RMSE) of 3.08 when training, and the performance fell slightly when testing. Even though, the correlation coefficient value (R) between the predicted value and the actual value of 0.9752 could be achieved, which means this model can predict the variation of effluent COD in general. The dynamic-state models under three kinds of shock loads, which were concentration, hydraulic, and bicarbonate buffer absent, showed good forecasting performance, the correlation coefficient values (R) all excelled 0.99. Among these three shocks, the dynamic LS-SVM model under bicarbonate buffer absent shock achieved the optimal performance and followed by the dynamic-state model under hydraulic shock. This paper provides a meaningful reference to improve the monitoring level of the anaerobic wastewater treatment process. [ABSTRACT FROM AUTHOR]

An inorganic-based bed biofilter was used to eliminate methane (CH) from an air stream under pseudo steady state, transient state (shock loads), and starvation conditions. Under pseudo steady state conditions, the effect of inlet CH concentration in the range of 1000-13,000 ppmv on the biofilter performance was studied. The air flow rate was kept constant at 3 L min, corresponding to an empty bed residence time (EBRT) of 6 min. The flexibility of the biofilter under transient conditions was evaluated by two strategies: Inlet loads (IL) varied from 13 to 65 g m h by changing inlet concentrations from 2000 to 10,000 ppmv or by changing air flow rates varied from 3 to 15 L min, separately. Finally, the effects of nutrients and CH starvations were evaluated. The biofilter performance was promising for the treatment of a wide range of concentrations of off gas emissions polluted with CH (1000-13,000 ppmv). For CH concentrations ranging from 1000 to 4000 ppmv, the removal efficiency (RE) remained higher than 75 %. The maximum elimination capacity (EC) obtained in this study was 45 g m h for an IL of 87 g m h. In case of sudden variations of ILs (13 to 65 g m h) either by changing the inlet concentration or by modifying the flow rate, the responses of the biofilter were almost instantaneous. [ABSTRACT FROM AUTHOR]

Precision-guided projectiles (PGPs) typically deployed in smart munitions are operated and guided by highly sophisticated embedded electronic systems (EES). These PGPs are subjected to severe shock loads resulting from the ignition of the propellant during their launch. These shock loads, which are typically characterised by high intensity, short duration and wave reflections at varied frequencies, often lead to the failure of the EES. It is the objective of this work to conduct a comprehensive multiphysics analysis of the launch process of PGPs accounting for coupling and interaction effects between the different media (propellant, PGP, confined volume and free space). Specifically, we investigated the entire launch process that include the ignition of the propellant to observe local and global features of the setback, set forward pressure and acceleration histories using explicit axisymmetric Lagrangian-Eulerian finite element simulations. In this work, we also examine the severity and frequency of the reflected waves as well as the springback of the PGPs resulting from these local oscillations as they exit the muzzle. In addition, the flight state transition due to muzzle exit in terms of pressure and flow velocity is also discussed. Our results reveal the complex phenomena associated with the dynamic response of the PGPs and pressurization process resulting from the ignition of propellant during launch that are characterized by high oscillatory pressure profiles and projectile springback. [ABSTRACT FROM AUTHOR]

Equations are provided for calculating and establishing a relationship in the form of an integral curve between emissions the probability of their occurrence. Regularities are revealed for the effect on emissions: number of fields and the number inter-electrode gaps (IEG) in a field, number of faulty gaps between electrodes, field electrode shaking regimes, and inter-electrode distance. Recommendations are formulated for electrostatic precipitator construction for effective cleaning conditions with prolonged operation. [ABSTRACT FROM AUTHOR]

Changes in the dielectric constant and dielectric loss tangent of water that was first subjected to impact loads under the action of an alternating magnetic field were determined quantitatively using a micro-wave system, which allows solution of the inverse problem. The results of measurements of the optical spectrum of water in the 'transmission' mode, which was subjected to a shock load, in comparison with the optical spectrum of distilled water, are described. [ABSTRACT FROM AUTHOR]

A procedure and results of experimental determination of the vibroaccelerations of a cylindrical shell filled with a continuum (water, clay, or sand) are presented. The dependence of the vibroaccelerations and natural frequencies of the shell on the density of the continuum is studied. It is established that the vibroaccelerations are maximum at resonance. [ABSTRACT FROM AUTHOR]

In the industrial operation of biotrickling filters for hydrogen sulfide (H2S) removal, shock loads or starvation was common due to process variations or equipment malfunctions. In this study, effects of starvation and shock loads on the performance of biotrickling filters for H2S removal were investigated. Four experiments were conducted to evaluate the changes of biomass and viable bacteria numbers in the biotrickling filters during a 24-d starvation. Compared to biomass, viable bacteria numbers decreased significantly during the starvation, especially when airflow was maintained in the absence of spray liquid. During the subsequent re-acclimation, all the bioreactors could resume high removal efficiencies within 4 d regardless of the previous starvation conditions. The results show that the re-acclimation time, in the case of biotrickling filters for H2S removal, is mainly controlled by viable H2S oxidizing bacteria numbers. On the other hand, the biotrickling filters can protect against shock loads in inlet fluctuating H2S concentration after resuming normal operation. When the biotrickling filters were supplied with H2S at an input of lower than 1700 mg/m3, their removal efficiencies were nearly 98% regardless of previous H2S input. [ABSTRACT FROM AUTHOR]

The paper outlines a method and results of experimental determination of vibratory stresses in a shell structure contacting with a medium. The stresses peak at the junction between the shell and the branch pipe. It is established that when the shell is in contact with the medium, the vibratory stresses are much higher, while the vibratory accelerations are much lower [ABSTRACT FROM AUTHOR]

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