IEEE 802.11 medium access control enhancements based on simultaneous multiple‐input multiple‐output bandwidth sharing

The demand for higher data rate has spurred the adoption of multiple‐input multiple‐output (MIMO) transmission techniques in IEEE 802.11 products. MIMO techniques provide an additional spatial dimension that can significantly increase the channel capacity. A number of multiuser MIMO system have been proposed, where the multiple antenna at the physical layer are employed for multiuser access, allowing multiple users to share the same bandwidth. As these MIMO physical layer technologies further evolve, the usable bandwidth per application increases; hence, the average service time per application decreases. However, in the IEEE 802.11 distributed coordination function‐based systems, a considerable amount of bandwidth is wasted during the medium access and coordination process. Therefore, as the usable bandwidth is enhanced using MIMO technology, the bandwidth wastage of medium access and coordination becomes a significant performance bottleneck. Hence, there is a fundamental need for bandwidth sharing schemes at the medium access control (MAC) layer where multiple connections can concurrently use the increased bandwidth provided by the physical layer MIMO technologies. In this paper, we propose the MIMO‐aware rate splitting (MRS) MAC protocol and examine its behavior under different scenarios. MRS is a distributed MAC protocol where nodes locally cooperate with one another to share bandwidth via splitting the spatial channels of MIMO systems. Simulation results of MRS protocol are obtained and compared with those of IEEE 802.11n protocol. We show that our proposed MRS scheme can significantly outperform the IEEE 802.11n in medium access delay and throughput. Copyright © 2012 John Wiley & Sons, Ltd.     

Managing connection costs in heterogeneous wireless networks

Common Radio Resource Management techniques have shown great promise in both enhancing network operation and user satisfication. Such gains are achieved through the joint management of the individual access technologies in a Heterogeneous Wireless Network. The objective of this work is to expand on the existing body of work to accommodate heterogeneity not just at the traditional access‐network level but to other connectivity modes such as dynamic spectrum access. Such modes affect operator profitability in both the long and short terms. Specifically, we explore the design of a cost‐management model that adapts to the short‐term variability in connectivity costs. We also display the operational aspects and effectiveness of this functionality through both simulation and an analytical model. Copyright © 2012 John Wiley & Sons, Ltd.     

Explosive spalling of normal strength concrete slabs subjected to severe fire

The first part of this paper presents an experimental investigation on explosive spalling of six full-scale normal strength reinforced concrete slabs subjected to conventional fire curve ISO834 and severe hydrocarbon fire curve, performed at the Fire Research Centre, University of Ulster, UK focusing on concrete thermal behaviour and the explosive spalling phenomenon. Each slab was loaded with 65% of its BS8110 design load and was heated from the bottom side only. Temperatures profile was recorded at three depths within the slabs and the moisture content was also measured before and after the tests. The deflection of the slabs was recorded at the middle of the 3 m span. The second part of the paper presents a numerical study on the normal concrete slabs using the finite element method. The concrete slabs were modelled including the embedded reinforcement to conduct a non-linear transient structural analysis taking into account cracks appearance and creep. A comparison between the experimental and the FEM results is presented in the paper.     

Printing Nanostructures with a Propelled Anti‐Pinning Ink Droplet

Striving for cheap and robust manufacturing processes has prompted efforts to adapt and extend methods for printed electronics and biotechnology. A new “direct‐write” printing method for patterning nanometeric species in addressable locations has been developed, by means of evaporative deposition from a propelled anti‐pinning ink droplet (PAPID) in a manner analogous to a snail‐trail. Three velocity‐controlled deposition regimes have been identified; each spontaneously produces distinct and well‐defined self‐assembled deposition patterns. Unlike other technologies that rely on overlapping droplets, PAPIDs produce continuous patterns that can be formed on rigid or flexible substrates, even within 3D concave closed shapes, and have the ability to control the thickness gradient along the pattern. This versatile low cost printing method can produce a wide range of unusual electronic systems not attainable by other methods.     

The Therapeutic Potential of Milk Extracellular Vesicles on Colorectal Cancer

Colorectal cancer remains one of the leading prevalent cancers in the world and is the fourth most common cause of death from cancer. Unfortunately, the currently utilized chemotherapies fail in selectively targeting cancer cells and cause harm to healthy cells, which results in profound side effects. Researchers are focused on developing anti-cancer targeted medications, which is essential to making them safer, more effective, and more selective and to maximizing their therapeutic benefits. Milk-derived extracellular vesicles (EVs) from camels and cows have attracted much attention as a natural substitute product that effectively suppresses a wide range of tumor cells. This review sheds light on the biogenesis, methods of isolation, characterization, and molecular composition of milk EVs as well as the therapeutic potentials of milk EVs on colorectal cancer.     

Enhanced meta-heuristic methods for industrial winding process modelling

Nonlinear industrial system modelling entails two critical phases: The first is selecting a method in order to estimate the parameter list values, and the second is selecting a proper model structure with a relatively short parameter list. Developing a comprehensive model for an industrial design process is critical for the model-based control system. This article presents a model-based strategy that aims to develop three linear and three nonlinear dynamic models using three well-known meta-heuristic optimization algorithms to simulate a challenging plant-wide process. As a case study, an industrial real winding process (WP) is targeted to accomplish the aim of this study. The algorithms have been optimized to find the best weights of the inputs of the WP with a key issue to effectively describe the behaviour aspects of the process. To test the validity of the developed models, a series of experiments were carried out on each of the developed linear and nonlinear models. Several relevant evaluation metric measures are used to demonstrate the models' performance level. The experimental results for training and test sets of 1250 independent samples for each set based upon the proposed modelling schemes show that the mean square error to correctly model the WP occurred in less than 0.001. A comparison of the developed intelligent linear and nonlinear models with the Auto-Regressive Integrated Moving Average (ARIMA) and Multiple Linear Regression (MLR) models obtained through the evaluation criteria asserts the effectiveness of the proposed models-based approaches.     

Nanoscale Sensor Technologies for Disease Detection via Volatolomics

The detection of many diseases is missed because of delayed diagnoses or the low efficacy of some treatments. This emphasizes the urgent need for inexpensive and minimally invasive technologies that would allow efficient early detection, stratifying the population for personalized therapy, and improving the efficacy of rapid bed‐side assessment of treatment. An emerging approach that has a high potential to fulfill these needs is based on so‐called “volatolomics”, namely, chemical processes involving profiles of highly volatile organic compounds (VOCs) emitted from body fluids, including breath, skin, urine and blood. This article presents a didactic review of some of the main advances related to the use of nanomaterial‐based solid‐state and flexible sensors, and related artificially intelligent sensing arrays for the detection and monitoring of disease with volatolomics. The article attempts to review the technological gaps and confounding factors related to VOC testing. Different ways to choose nanomaterial‐based sensors are discussed, while considering the profiles of targeted volatile markers and possible limitations of applying the sensing approach. Perspectives for taking volatolomics to a new level in the field of diagnostics are highlighted.     

A Parametrics Architecture for Design, Management, and Coordination in a Collaborative AEC Environment

This article describes a unified system architecture for representation and reasoning in a concurrent, collaborative architectural/engineering/construction (AEC) environment. The architecture is built on a formal unified modeling methodology for products and processes based on parametrics techniques. The architecture forms the core of a domain‐independent shell that could be used for incremental knowledge integration. The integrated knowledge base could be used at any point of inference to propagate changes in data values or knowledge items using parameter‐dependency networks. The article concentrates on the representation standards of the core elements of the collaborative architecture. It starts by describing the needs set by the nature of project organization in the AEC industry as well as the research philosophy. The article briefly illustrates the generic parametric representation and inference foundation, including the role of exogenous variables in domain knowledge control. The article concentrates on the standards of object‐oriented representation that form the core of domain modeling and knowledge integration. The representation covers various tasks such as context knowledge control for version management, knowledge integration with other systems, and efficient propagation control. The article shows that the careful use of domain knowledge in modeling the problem and controlling inference through exogenous variables provides guidelines toward creating sound standards for representation.     

A fast Josephson SFQ shift register

A Josephson SFQ (single flux quantum) shift register circuit operating under a two-phase power was designed and tested. The test cell was fabricated using the Nb/AlO_x/Nb junction SNEAP process. The main data latch is DC biased; the data storage is accomplished by the transfer of a single flux quantum in or out of a SQUID (superconducting quantum interference device) superconducting loop. A two-phase sinusoidal clock with offset is used to operate the circuit. Simulations verify that the operating frequency can go beyond 70 GHz, with operating margins exceeding 20%. Preliminary measurements indicate that the circuit operates as intended