An Efficient Modified Dragonfly Optimization Based MIMO-OFDM for Enhancing QoS in Wireless Multimedia Communication

Wireless Personal Communications - Multiple inputs multiple outputs (MIMO) is a reliable technique which can manage the increased wireless data traffic in the future generation of wireless...     

Finite-element simulation of induction heat treatment

An efficient finite-element procedure has been developed for the analysis of induction heat treatment problems involving nonisothermal phase changes. The finite-element procedure first simulates the magnetic field developed when currents flow through an induction coil by solving Maxwell’s electromagnetic field equations; at the following step, it calculates the temperature distribution in the workpiece due to eddy currents induced by the magnetic field. The final stage of the simulation involves the determination of the distributions of residual stress, hardness, and microstructure in the workpiece. The finite-element analysis includes temperature-dependent material properties, changes in permeability of the workpiece at the Curie temperature, a mixed hardening rule to describe the material constitutive model, and the incorporation of time-temperature-transformation (TTT) diagram. The procedure was applied to the simulation of the induction hardening of 1080 steel bar. Firstly, the magnetic field and temperatures developed in the workpiece during (a) the induction heating of an infinitely long 1080 steel cylinder by a single encircling coil and (b) the induction heating of a semi-infinite half-space by a single coil suspended above it were calculated using the finite-element procedures. These were validated by comparing them with analytical solutions derived for these configurations using a Green’s function method. Finally, to demonstrate the predictive capability and practical applicability of the current finite-element procedure, two examples pertaining to the induction heat treatment of an infinite 1080 steel bar of square cross section and a notched finite 1080 steel cylinder of circular cross section were analyzed to predict the magnetic field, temperature, and residual stress distributions. The current finite-element procedure could be used as a powerful design tool for linking induction heat treating parameters with the mechanical property attributes of the heat treated component.     

Finite-element simulation of moving induction heat treatment

An efficient finite-element procedure with a remesh scheme has been developed for the analysis of the moving induction heat treatment process, wherein relative motion occurs between the coil and the workpiece. In this procedure, the magnetic field is first simulated by using an updated mesh that tracks the moving coil position; the moving heat source within the workpiece material is derived from the magnetic field. The heat equation is then solved to obtain the temperature field created by the heat source. The procedure has been applied to calculate the temperature distributions in 1080 carbon steel cylinders during induction heating. The calculations have been validated by comparison with analytical solutions for the temperature distribution obtained using Green’s function methods. Finally, the temperature, residual stress, and microstructure distributions in quenched 1080 steel cylinders have been obtained using the finite-element procedure. Quenching of the heated cylinders, by both a moving cooling ring and a stationary liquid bath, has been analyzed. The finite-element procedure presented incorporates temperature-dependent material properties, phase transformations occurring in the 1080 steel, the change in magnetic permeability of the 1080 steel at the Curie temperature, and an elastoplastic stress model based on a mixed hardening rule. The simulation results demonstrate that the finite-element procedure could be applied to a variety of moving induction heat treatment problems to determine the residual stress and microstructure distributions in the heat-treated component. It also could be used in the design of process parameters and coils.     

Key-dependent 3D model hashing for authentication using heat kernel signature

Multimedia-based hashing is considered an important technique for achieving authentication and copy detection in digital contents. However, 3D model hashing has not been as widely used as image or video hashing. In this study, we develop a robust 3D mesh-model hashing scheme based on a heat kernel signature (HKS) that can describe a multi-scale shape curve and is robust against isometric modifications. We further discuss the robustness, uniqueness, security, and spaciousness of the method for 3D model hashing. In the proposed hashing scheme, we calculate the local and global HKS coefficients of vertices through time scales and 2D cell coefficients by clustering HKS coefficients with variable bin sizes based on an estimated L² risk function, and generate the binary hash through binarization of the intermediate hash values by combining the cell values and the random values. In addition, we use two parameters, bin center points and cell amplitudes, which are obtained through an iterative refinement process, to improve the robustness, uniqueness, security, and spaciousness further, and combine them in a hash with a key. By evaluating the robustness, uniqueness, and spaciousness experimentally, and through a security analysis based on the differential entropy, we verify that our hashing scheme outperforms conventional hashing schemes.     

Heat penetration characteristics and shelf‐life studies of mushrooms in brine processed in retort pouches

White button mushrooms were washed, blanched and cut longitudinally into two halves. 100 g mushroom halves was placed into each retort pouch and 90 ml hot brine (2% salt, 0.1% citric acid) was added. Retort pouches (105 µm thick) had an outer polyester layer (12.5 µm), a middle aluminium layer (12.5 µm) and an inner cast polypropylene layer (80 µm); pouch size was 20 × 16 cm, seal size 10 mm and lip size 4 mm. Pouches were fixed with thermocouples for recording the core temperature of the mushroom pieces, using a data recorder and a computer. After sealing and over‐pressure retorting at F₀ = 9.6, the pouches were stored at the ambient conditions. The heat penetration parameters were calculated. The heating curve obtained was logarithmic in nature. Sensory evaluation of mushroom curry prepared from the stored mushrooms showed that the product had high acceptability (7.9 on a scale of 10) which reduced very slightly (to 7.5) during storage for 12 months. No deformity, leakage or spoilage was noticed and the product remained sterile and acceptable even after 12 months of storage at the ambient conditions (20–30°C). Copyright © 2004 John Wiley & Sons, Ltd.     

The Effects of Process Characteristics on the Value of B2B E-Procurement

Even as more organizations are moving towards implementing Web-based B2B procurement solutions, they are unsure of the real benefits of the Web. In other words, what is the value of B2B e-procurement to an organization and how to measure this value? What factors affect this value? In this paper, we discuss an evaluation framework to determine the value of B2B e-procurement and the effect of process characteristics on the value. We use an empirical study to highlight the different value created by different procurement types. We then develop a more comprehensive economic model to capture the additional effects of demand volume and process complexity. The integration of theoretical and empirical approaches provides a strong foundation to develop and evaluate useful adoption strategies for B2B e-procurement.     

Kalman filtering with constrained output injection

In applications involving large scale systems such as discretized partial differential equations, it is often of interest to use data to estimate state variables associated with a subregion of the spatial domain. In this paper we derive an extension of the classical Kalman filter in which data injection is confined to a subspace of the system states.