A simple mass oscillator metasurface design with linear phase shift

In this paper, a simple mass oscillator metasurface is designed, which can regulate the phase shift of flexural wave covering 0-2π by adjusting the number of mass oscillators on the connecting bar. Based on the forced vibration theory, there is a simple approximately linear relationship between the number and phase shift of mass oscillators, which can more intuitively and accurately predict the phase of different number of mass oscillators, and then realize the metasurface design of mass oscillators with different requirements. Therefore, arbitrary regulation of flexural waves, such as abnormal refraction, beam focusing, and self-acceleration, can be realized by reasonably arranging the number of mass oscillators. The results show that the proposed metasurface can be greatly simplified both in the establishment of phase shift relation and in the fabrication of structure configuration, and will have broad application potential in the engineering field.

Structural Lattice Topology and Material Optimization for Battery Protection in Electric Vehicles Subjected to Ground Impact Using Artificial Neural Networks and Genetic Algorithms

A critical external interference that often appears to pose a safety issue in rechargeable energy storage systems (RESS) for electric vehicles (EV) is ground impact due to stone impingement. This study aims to propose the new concept of the sandwich for structural battery protection using a lattice structure configuration for electric vehicle applications. The protective geometry consists of two layers of a twisted-octet lattice structure. The appropriate lattice structure was selected through topology and material optimization using an artificial neural network (ANN), genetic algorithms (GA), and multi-objective optimization with technique for order of preference by similarity to ideal solution (TOPSIS) methods. The optimization variables are the lattice structure relative density, ρ¯, angle, θ, and strength of the materials, σy. Numerical simulations were used to model the dynamic impact loading on the structures due to a conical stone mass of 0.77 kg traveling at 162 km/h. The two-layer lattice structure configuration appears to be suitable for the purposes of RESS protection. The optimum configuration for battery protection is a lattice structure with an angle of 66°, relative density of 0.8, and yield strength of 41 MPa. This optimum configuration can satisfy the safety threshold of battery-shortening deformation. Therefore, the proposed lattice structure configuration can potentially be implemented for electric vehicle applications to protect the battery from ground impact.

Centralized on-line monitoring system for pipeline and cable environment and fresh air of air conditioning

Aiming at the problem of on-line centralized monitoring error of pipeline and cable environment and fresh air of air conditioning, a utility model is designed, a centralized monitoring system of pipeline and cable environment and fresh air of air conditioning is disclosed, the system structure configuration is optimized, and the system performance is improved by combining multiple central air conditioning controllers, data processors, acquisition servers and other equipment, combined with LabVIEW technology, the system software function and operation process are improved. Finally, the experiment proves that the centralized online monitoring system for pipeline and cable environment and air conditioning fresh air can better reduce the monitoring error and ensure the real-time monitoring quality of pipeline and cable environment and air conditioning fresh air.

Bacteriophage Structure, Classification, Assembly and Phage Therapy

Current emergence of multidrug resistance and limitations in the development of the new antibiotics has proposed the problem of treating bacterial infections more challenging. This scenario may lead to the fear of failure in treating the multidrug resistant (MDR) bacterial infections and fuelled the uses of bacteriophages as an alternative of the conventional antibiotics in the post antibiotic era.So it is very much essential to know about the details of phage life cycle, assembly of phage complete structure, configuration and function of phage associated proteins etc. Although phages have been discovered a century ego, detailed study about lytic phages are gaining more interest in global fight against MDR bacterial species. This review has highlighted the basic knowledge of bacteriophage with the past and present scenario of several clinical studies targeting the MDR bacterial species. On the other hand it also discussed about the other uses of phages except human clinical trials.

The Phenomenological Theory of Turbulence and the Scour Evolution Downstream of Grade-Control Structures under Steady Discharges

A more complete understanding of scour mechanisms for flows downstream of grade-control structures, including their temporal evolution, has the potential to lead to improved predicting tools for design. To date, design equations have been mostly derived empirically, i.e., by parametric modelling (at generally-small scales) corresponding to specific structure configurations, and for limited ranges of hydraulic conditions. Although these approaches allowed different authors to propose many empirical and/or semi-empirical equations, they lack generality and may lead to incorrect estimations when applied outside their ranges of validity. First-principles-based methods with solid calibration and validation procedures can overcome these issues. Following recent theoretical advancements presented elsewhere by the last three authors, in this work we analyze and test the predictive capability of a scour evolution model based on the phenomenological theory of turbulence (PTT) by using a large dataset pertaining to different grade-control structures. Although the PTT model was developed (and validated) for scour evolution caused by oblique and vertical plunging jets, we show that its basic assumptions are still valid for the addressed low-head structures, encompassing rock structures, stepped gabion weirs, rock and bed sills, and others. Furthermore, we also provide interesting insights on scour evolution by contrasting the predicting capability of our model against experimental data by different authors for specific structures. Results of the comparison conclusively show that the PTT model has a general validity and represents a trustable tool to estimate scour evolution regardless of the structure configuration and hydraulic conditions.