Hand-Off Performance of the Integrated Cellular and Ad Hoc Relaying (iCAR) System

In this paper, we study the hand-off performance of a wireless system with heterogeneous technologies called iCAR (Integrated Cellular and Ad hoc Relaying). In iCAR, hand-offs can occur not only from a Base Transceiver Station (BTS) to another BTS, but also from a BTS to a so-called Ad hoc Relaying Station (ARS) in the form of relaying, as well as from an ARS back to a BTS. The latter two types of hand-offs effectively increase the hand-off buffer time and thus reduce the call dropping probability. We develop an analytical model for the hand-off performance in iCAR. In addition, we verify the analytical model via simulations and quantify the hand-off performance benefits of the iCAR system over conventional cellular systems. It is anticipated that the analytical and simulation models reported in this paper will serve as a guideline to other researches on the inter-system hand-off involving heterogenous wireless technologies.     

A web-based decision support system for multi-criteria inventory classification using fuzzy AHP methodology

We propose an inventory classification system based on the fuzzy analytic hierarchy process (AHP), a commonly used tool for multi-criteria decision making problems. We integrate fuzzy concepts with real inventory data and design a decision support system assisting a sensible multi-criteria inventory classification. We report on a study conducted in a small electrical appliances company and validate the design of the proposed multi-criteria inventory classification system and its underlying fuzzy AHP model.     

Position‐Based Simulation of Elastic Models on the GPU with Energy Aware Gauss‐Seidel Algorithm

In this paper, we provide a smooth extension of the energy aware Gauss‐Seidel iteration to the Position‐Based Dynamics (PBD) method. This extension is inspired by the kinetic and potential energy changes equalization and uses the foundations of the recent extended version of PBD algorithm (XPBD). The proposed method is not meant to conserve the total energy of the system and modifies each position constraint based on the equality of the kinetic and potential energy changes within the Gauss‐Seidel process of the XPBD algorithm. Our extension provides an implicit solution for relatively better stiffness during the simulation of elastic objects. We apply our solution directly within each Gauss‐Seidel iteration and it is independent of both simulation step‐size and integration methods. To demonstrate the benefits of our proposed extension with higher frame rates, we develop an efficient and practical mesh coloring algorithm for the XPBD method which provides parallel processing on a GPU. During the initialization phase, all mesh primitives are grouped according to their connectivity. Afterwards, all these groups are computed simultaneously on a GPU during the simulation phase. We demonstrate the benefits of our method with many spring potential and strain‐based continuous material constraints. Our proposed algorithm is easy to implement and seamlessly fits into the existing position‐based frameworks.     

Learning a Generative Model for Multi‐Step Human‐Object Interactions from Videos

Creating dynamic virtual environments consisting of humans interacting with objects is a fundamental problem in computer graphics. While it is well‐accepted that agent interactions play an essential role in synthesizing such scenes, most extant techniques exclusively focus on static scenes, leaving the dynamic component out. In this paper, we present a generative model to synthesize plausible multi‐step dynamic human‐object interactions. Generating multi‐step interactions is challenging since the space of such interactions is exponential in the number of objects, activities, and time steps. We propose to handle this combinatorial complexity by learning a lower dimensional space of plausible human‐object interactions. We use action plots to represent interactions as a sequence of discrete actions along with the participating objects and their states. To build action plots, we present an automatic method that uses state‐of‐the‐art computer vision techniques on RGB videos in order to detect individual objects and their states, extract the involved hands, and recognize the actions performed. The action plots are built from observing videos of everyday activities and are used to train a generative model based on a Recurrent Neural Network (RNN). The network learns the causal dependencies and constraints between individual actions and can be used to generate novel and diverse multi‐step human‐object interactions. Our representation and generative model allows new capabilities in a variety of applications such as interaction prediction, animation synthesis, and motion planning for a real robotic agent.     

Effect of pin offset on the mechanical properties of friction stir welded AA 6013 aluminum alloy plates

In this study, AA 6013 aluminum plates were butt‐welded with friction stir welding via pin offset technique. Macrostructural observations revealed that kissing bonds, originated from the broken oxide layers, were found to occur in the welded joints. The fracture location of welded joints after tensile tests was found to be outside the joint area, revealing that kissing bonds which were formed in the stir zone exhibited no detrimental effect on the mechanical properties of joints. Microstructural observations revealed that phases belonging to Mg₂Si, Al₄Cu₂Mg₈Si₇ and Al(MnFe)Si were observed in the x‐ray diffraction pattern of friction stir welded joints. The highest tensile strength with a value of 206 MPa was achieved with the process parameters of 1.5 mm pin offset towards the advancing side and 500 min^?1 tool rotational speed, leading the ratio of tensile strength of joint to ultimate tensile strength of base metal, also known as joint efficiency, to reach 74 %.     

A cross-layer multi-hop cooperative network architecture for wireless ad hoc networks

In this paper, a novel decentralized cross-layer multi-hop cooperative network architecture is proposed and presented. This cross-layer architecture introduces a new cooperative flooding scheme and two decentralized opportunistic cooperative forwarding mechanisms based on randomized coding, and a Routing Enabled Cooperative Medium Access Control (RECOMAC) protocol that enables cooperative forwarding, while incorporating physical, medium access control (MAC) and routing layers. RECOMAC employs randomized coding to realize cooperative diversity, so that relay selection and actuation mechanisms are alleviated and the MAC costs are reduced. The coded packets are routed in the network via the proposed cooperative forwarding schemes, which opportunistically form cooperative sets within a region, not needing a prior route to be established. Essentially, in the RECOMAC architecture, the routing layer functionality is submerged into the MAC layer to provide seamless cooperative communication, while the messaging overhead to set up routes, select and actuate relays is reduced. We evaluate the performance of RECOMAC in terms of network throughput, delay and MAC and routing overhead, in comparison to the conventional architecture based on the well-known IEEE 802.11 MAC and Ad hoc On Demand Distance Vector (AODV) routing protocols. RECOMAC is shown to provide quite significant improvement by an order of magnitude difference in all investigated performance metrics, under a variety of scenarios, considering different network sizes, static and mobile scenarios and networks with multiple flows.     

Mechanical and electromechanical properties of piezoelectric ceramic fibers drawn by the alginate gelation method

Piezoelectric ceramic fibers are widely used in piezocomposite devices. The various methods that are used to draw ceramic fibers differ in the way the fiber form is obtained, which in return closely affects the density, uniformity and the properties of the fibers that are obtained at the end. In this study, the processing-property relationship in the piezoceramic fibers drawn using the alginate gelation method is investigated, with a focus on the mechanical and electrical properties of individual fibers. Fibers with a Weibull strength of 65.3 MPa, remanent polarization of 22 μC/cm² and a total bipolar field induced strain of 0.25% under an electric field of 2.5 kV/mm, piezoelectric coefficient of 300 pm/V and dielectric constant of 3323 were produced. 1-3 piezocomposite devices prepared from these fibers had a 6 dB higher free-field voltage sensitivity and a 50% wider bandwidth compared to a solid disk transducer of the same dimensions.     

Buttermilk as milk powder and whey substitute in compound milk chocolate: Comparative study and optimisation

The aim of this study was to investigate the optimal concentration of milk, whey and buttermilk powder by using mixture design for the formulation of compound milk chocolate. The influence of buttermilk as a milk and whey substitute on the main physicochemical parameters of compound milk chocolate was investigated. The optimisation of the variables indicated that using 35.660% milk powder, 27.957% whey powder and 36.383% buttermilk produced the optimum milk chocolate with the highest desirability without undesirable changes in the quality properties. Chocolates containing equal amounts of buttermilk and milk powder and also equal amounts of whey powder and buttermilk powder demonstrated high consumer acceptability.     

Effect of different modified atmosphere packaging on microbial quality,oxidation and colour of a seasoned ground beef product (meatball)

The effects of different modified atmosphere packaging (MAP) on microbial quality, oxidation and colour of meatballs were investigated. Meatballs were prepared in our laboratory and packaged in vacuum or in different gases: combinations of O₂ (0, 2, 21%) and CO₂ (0, 33, 66, 100%) with N₂ as balance gas. Total microbial count, thiobarbituric acid reactive substances and colour were determined during storage at 3°C for 3 weeks. Total microbial count remained unchanged at around 6.3 LogCFU/g in vacuum and 100% CO₂ packages after 7 days, and slightly increased afterwards. The microbial count was higher in other packages and increased to 7.6 LogCFU/g after 21 days storage. Oxidation was inhibited by reduced O₂ and increased CO₂ in the packages. Packages with low O₂ maintained colour (a‐values) to a greater extent than the packages with higher O₂ levels. MAP containing 1–3%O₂ with 33%CO₂ inhibited microbial growth, oxidation and colour change in meatballs. Copyright © 2009 John Wiley & Sons, Ltd.