Stochastic perturbation-based finite element for deflection statistics of soft core sandwich plate with random material properties

The effect of random variations in material properties of laminated sandwich plates on the transverse deflections is investigated. An improved higher-order plate model is proposed earlier by the authors, which satisfies the transverse shear stress continuity conditions at the layer interfaces including the zero transverse shear stress conditions at the plate top and bottom surfaces. The theory assumes the variation of in-plane displacements to be cubic with discontinuities in the transverse shear strains at the layer interfaces, while the transverse displacements varies quadratically across the core thickness, thereby including transverse normal deformation of the soft core. The core is considered to behave as a 3-D elastic medium. To obtain the second-order statistics of deflections of sandwich plate, a stochastic C⁰ finite element (FE) based on the first-order perturbation technique is developed, where the lamina properties are considered as basic random variables while the other system properties are assumed to be deterministic. The performance of the improved stochastic laminated sandwich model is demonstrated through comparison of mean and standard deviations (SDs) of deflections obtained through independent Monte Carlo simulations and by comparison with results available in literature.     

Model for radiation emission EMC measurement at OATS: Issues and approaches

Open area-test site (OATS) is envisaged to be one of the key components in measuring radiation emissions for new electronics products in noisy environment, providing flexible high resolution backhaul over expensive anechoic chamber for early investigation. While single chamber cost suffer from range of operating frequencies constraints, equipping OATS with flexible ambient masking module (FAM) can significantly alleviate the ambient problem and increase the aggregate precision available to electronics product to meet local electromagnetic compatibility (EMC) standards. The goal of this classification algorithm is to characterize source generated data concealed within ambient and then to categorize them according to their attribute. In this paper we examine the unique constraint of site attenuation and identify the key factors governing assignment schemes, with particular reference to interference, precision of transducers and noise profiles. After presenting the taxonomy of existing kind of pass type data assignment, we describe a real time data assignment architecture which incorporates the radiation emissions together with class issues in order to minimize interference with ambient and how its integration can be exploited to achieve chamber efficiency is discussed. The preliminary performance results validate the design choices of the parameters and confirm the potential impact of the price paid.     

3D printing in aerospace and its long-term sustainability

ABSTRACT

Astonishingly 3D printing has excited the world of aerospace. This paper takes stock of the popular 3D printing processes in aerospace. Reasons for their popularity over the traditional manufacturing processes are dwelled upon. Materials developed specially for aerospace applications along with their characteristics are discussed. Ongoing activities related to 3D printing at various companies and organisations around the world are looked into. Project works in the area of extra-terrestrial printing are also highlighted. Even though 3D printing processes are operationally simple, they do have limitations in terms of the type, quality, and quantity of the materials they can handle. This paper underlines these points while discussing drawbacks of the printed components. Challenges associated with 3D printing in microgravity are also touched upon. Finally, a glimpse is taken into the future appearance of aerospace industry with 3D printing.     

Nanocellulose-Based Composites and Bioactive Agents for Food Packaging

Global environmental concern, regarding the use of petroleum-based packaging materials, is encouraging researchers and industries in the search for packaging materials from natural biopolymers. Bioactive packaging is gaining more and more interest not only due to its environment friendly nature but also due to its potential to improve food quality and safety during packaging. Some of the shortcomings of biopolymers, such as weak mechanical and barrier properties can be significantly enhanced by the use of nanomaterials such as nanocellulose (NC). The use of NC can extend the food shelf life and can also improve the food quality as they can serve as carriers of some active substances, such as antioxidants and antimicrobials. The NC fiber-based composites have great potential in the preparation of cheap, lightweight, and very strong nanocomposites for food packaging. This review highlights the potential use and application of NC fiber-based nanocomposites and also the incorporation of bioactive agents in food packaging.     

Performance of Data-Rate Analysis of Massive MIMO System Using User Grouping

Wireless Personal Communications - The major challenges in massive MIMO networks are to increase the system throughput and capacity with low complexity and reliability of the wireless communication...     

Unsupervised on-line method to diagnose unbalanced voltage in three-phase induction motor

Neural Computing and Applications - In this paper, an unsupervised automatic method based on a current signature neural network (NN) is presented to on-line diagnose stator fault without the...     

Controlled synthesis of dense MgFe2O4 nanospheres by ultrasonic spray pyrolysis technique: Effect of ethanol addition to precursor solvent

We present the results of controlled synthesis of spherical shape magnesium ferrite (MgFe₂O₄) dense nanoparticles by using ultrasonic spray pyrolysis (USP) method without any post-annealing processes. A new strategy was proposed to improve nano-crystallinity and observed morphology by ethanol (EtOH) addition in the initial precursor solution of MgFe₂O₄. Influence of EtOH, not only decrease the synthesized secondary particle size but also enhancing crystallization into MgFe₂O₄ single phase cubic structure. We observe that average nanosphere size decrease from 220 to 189?nm but increases of crystallite size from 9.6 to 19.2?nm with increasing the amount of EtOH from 0 to 20?vol%. Also, surface morphology revealed that nanospheres with some irregular shape and rough surface appear in case of EtOH additives. The magnetic properties are studied and different parameters viz. saturation magnetization, remanence, and coercivity have been correlated with crystallite size.     

A mathematical model to predict the strength of aluminum alloys subjected to precipitation hardening

A number of alloys, notably most of the aluminum alloys, can be heat treated by aging. This aging due to time-dependent precipitation hardening increases the strength and hardness as well as modifying other mechanical properties. Precipitation hardening has been a popular strengthening mechanism for many decades; therefore, extensive information is available in literature about the precipitation-hardening response of various series of aluminum alloys. The age-har dening response of these alloys is usually represented in graphical form as plotted between property changes and aging time for different temperatures. In designing a suitable precipitation-hardening strategy, one can refer to these graphs. However, for automatic control of aging furnaces, as well as for decision making regarding optimal selection of aging conditions (time/temperature combination), it is desirable to express these relationships in a formal mathematical structure. A mathematical model is developed in this article for widely used heat treatable aluminum alloys used in the extrusion industry. This model is a condensed representation of all σ=f(T, t) curves in different series of aluminum alloys, and the parameters of this model characterize the various compositions of the alloys in the series.