Hybrids for finishing cotton fabric with durable handle performance

New poly(acrylic acid/epichlorohydrin) hybrids were prepared under different polymerization conditions and the proper hybrid was used as a stiffening agent or what may be called hand builder. The latter was incorporated in dimethyloldihydroxy ethylene urea (DMDHEU) finishing formulation and the onset of this on fabric performance as monitored by nitrogen content, wrinkle recovery angle, tensile strength, stiffness, dyeability, and oily stain release was studied. Durability of the new finish was also examined. Results disclose substantial improvement in fabric performance and imply that the hybrid in question acts as a durable hand builder through fixation via its hydroxyl groups within the DMDHEU finish which, in turn, is chemically bonded to cotton cellulose. Scanning electron microscopy of finished fabric revealed that this chemical bonding resulted in hybrid encapsulation, deposition and/or coating of fabric fibers.     

Distributed opportunistic scheduling for MIMO underlay cognitive radio networks

Cognitive radio networks have emerged to improve the utilization of the scarce spectrum. In this paper, we propose a distributed resource allocation algorithm that allocates resources opportunistically to the secondary users in a multiple‐input multiple‐output environment. In order to reduce the complexity and cost, antenna selection schemes are employed to allow the secondary communication using a single radio frequency chain. The proposed algorithm is proved theoretically and using simulations, to give a performance very close to that of a centralized one with lower delay and overhead. Furthermore, we introduce two techniques for the proposed algorithm based on the allowable data rates referred to as limited and maximum rates. We derive closed‐form expression for the consumed power and tight upper bounds for the average throughput achieved by each technique. A comparison between the proposed techniques is also provided. Both simulations and analytical results show that the proposed algorithm achieves high throughput with low complexity. Moreover, the results show that the tightness of the bounds improves with the diversity order. Finally, the proposed techniques are compared with two suggested random schemes to investigate their effectiveness. Copyright © 2016 John Wiley & Sons, Ltd.     

Robust and Efficient OFDM Synchronization for FPGA-Based Radios

Orthogonal frequency division multiplexing (OFDM) is a popular modulation technique that can combat impulsive noise, is robust to multipath fading, is spectrally efficient, and can allow flexible allocation of spectrum. It has become a key standard in cognitive radio systems as well as an enabling technology for mobile data access systems. An OFDM receiver’s performance is heavily impacted by the accuracy of its symbol timing offset (STO) and carrier frequency offset (CFO) estimation. This paper proposes a novel OFDM synchronization method that combines robust performance with computational efficiency. FPGA prototyping is used to explore the trade-off between the number of computations to be performed and computation word length with respect to both synchronization performance and power consumption. Through simulation, the proposed method is shown to provide accurate fractional CFO estimation as well as STO estimation in a range of channels. In particular, it can yield excellent synchronization performance in the face of a CFO that is larger than many state-of-the-art synchronization implementations can handle. The system implementation demonstrates efficient resource usage and reduced power consumption compared with existing methods, and this is explored as a fine-grained trade-off between performance and power consumption. The result is a robust method suitable for use in low-power radios, enabling less precise analog front ends to be used.     

Virtualized Execution and Management of Hardware Tasks on a Hybrid ARM-FPGA Platform

Emerging hybrid reconfigurable platforms tightly couple capable processors with high performance reconfigurable fabrics. This promises to move the focus of reconfigurable computing systems from static accelerators to a more software oriented view, where reconfiguration is a key enabler for exploiting the available resources. This requires a revised look at how to manage the execution of such hardware tasks within a processor-based system, and in doing so, how to virtualize the resources to ensure isolation and predictability. This view is further supported by trends towards amalgamation of computation in the automotive and avionics domains, where such properties are essential to overall system reliability. We present the virtualized execution and management of software and hardware tasks using a microkernel-based hypervisor running on a commercial hybrid computing platform (the Xilinx Zynq). The CODEZERO hypervisor has been modified to leverage the capabilities of the FPGA fabric, with support for discrete hardware accelerators, dynamically reconfigurable regions, and regions of virtual fabric. We characterise the communication overheads in such a hybrid system to motivate the importance of lean management, before quantifying the context switch overhead of the hypervisor approach. We then compare the resulting idle time for a standard Linux implementation and the proposed hypervisor method, showing two orders of magnitude improved performance with the hypervisor.     

Influence of microstructure size on the plastic deformation kinetics, fatigue crack growth rate, and low-cycle fatigue of solder joints

The influence of microstructure size on the plastic deformation kinetics, fatigue crack growth rate and low-cycle fatigue of eutectic Sn-Pb solder joints is reviewed. The principal microstructure feature considered is the average eutectic phase size d=(d_Pb+d_Sn)/2. The effect of an increase in reflow cooling rate (which gave a decrease in d) on the flow stress and on fatigue life was irregular at 300K, depending on the stress or strain level and cooling rate. In contrast, a consistent increase in fatigue life with decrease in d occurred for thermomechanical cycling between −30° and 130°C. Constitutive equations for plastic deformation and fatigue crack growth rate are presented which include the microstructure size. It appears that the rate-controlling deformation mechanism is the intersection of forest dislocations in the Sn phase. The mechanism for both static and dynamic phase coarsening appears to be grain boundary diffusion with a t^1/4 time law. Some success has been achieved in predicting the cyclic stress-strain hysteresis loops and fatigue life, including the influence of the as-reflowed microstructure size and its coarsening. Additional definitive studies are however needed before we can accurately predict the fatigue life of solder joints over the wide temperature range and conditions experienced by electronic packages.     

Plastic deformation kinetics of fine-grained alumina

The plastic deformation kinetics of a commercial fine-grained alumina with ∼300 ppm MgO and grain sizes from 1.4 to 2.9 μm were determined in tension at 1475 °C to 1600 °C and strain rates from 10⁻⁵ to 10⁻³ s⁻¹, employing stress relaxation (SR) as the principal test mode. The constants in the Weertman-Dorn (W-D) equation were determined and had the following values: A=2.9±0.5×10⁹, n=2.2±0.1, p=1.9±0.1, Q=492±3 kJ/mole, and threshold stress σ ₀=0. These constants are in accord with grain boundary sliding (GBS) accommodated by dislocation glide and climb with Al³⁺ ion lattice diffusion as the rate-controlling mechanism.     

Spatiotemporal Control over Molecular Delivery and Cellular Encapsulation from Electropolymerized Micro‐ and Nanopatterned Surfaces

Bioactive, patterned micro‐ and nanoscale surfaces that can be spatially engineered for three‐dimensional ligand presentation and sustained release of signaling molecules represent a critical advance for the development of next‐generation diagnostic and therapeutic devices. Lithography is ideally suited to patterning such surfaces due to its precise, easily scalable, high‐throughput nature; however, to date polymers patterned by these techniques have not demonstrated the capacity for sustained release of bioactive agents. Here a class of lithographically defined, electropolymerized polymers with monodisperse micro‐ and nanopatterned features capable of sustained release of bioactive drugs and proteins is demonstrated. It is shown that precise control can be achieved over the loading capacity and release rates of encapsulated agents and this aspect is illustrated using a fabricated surface releasing a model antigen (ovalbumin) and a cytokine (interleukin‐2) for induction of a specific immune response. Furthermore, the ability of this technique to enable three‐dimensional control over cellular encapsulation is demonstrated. The efficacy of the described approach is buttressed by its simplicity, versatility, and reproducibility, rendering it ideally suited for biomaterials engineering.     

Separation of Paraffin Wax Using Solvent Fractionation

In order to separate and characterize some grades of paraffin waxes from El-Ameria crude waxes (slack waxes), a one-stage fractional crystallization technique has been done to separate the paraffin waxes with different characteristics by using different solvents and solvent mixtures at ambient temperature of 20°C and fixed dilution and washing solvent ratios (S/F) of 4:1 and 2:1 by weight, respectively. The fractionating solvents used are n-hexane, methyl isobutyl ketone (MIBK), dioxane, ethyl acetate, and butyl acetate as a single solvent and a mixture of methyl ethyl ketone (MEK) containing benzene (B) and toluene (T) as a mixed solvent. The resulting data revealed that dioxane and n-hexane solvents are not suitable for fractional crystallization of slack waxes, and the most suitable solvents for separating paraffin waxes with the standard specifications are ethyl and butyl acetates, MIBK, and the mixture of MEK, B, and T (60:20:20 by weight, respectively).     

Combined biological–chemical (Ozone) treatment of wastewaters containing chloroguaiacols

Biological degradation of chloroguaiacols contained in sulphite pulp chlorine bleaching wastewater was studied in four parallel biological fluidised bed reactor systems—one single aerobic, one single anaerobic and two combined anaerobic–aerobic reactors. At low loading rates, trichloroguaiacols were removed nearly quantitatively. 4,5-Dichloroguaiacol was only partly removed. At high loading rates the anaerobic–aerobic recycle reactor removed individual guaiacols more than the other reactors. Only 4,5,6-trichloroguaiacol was removed best by the anaerobic–aerobic reactors in series. Even mixed culture biofilms adapted during several years of continuous operation did not satisfactorily remove these compounds. Synthetic wastewater, containing chlorinated guaiacols, treated with ozone produced formate and oxalate and quantitatively inorganic chloride. Combined ozonation–biotreatment in two reactors in series as well as in a recycle system allowed complete removal of all individual chlorinated guaiacols (< 1 μmol m^?3 remained). The efficiency of non-purgable organic carbon removal could be increased from ≤0.55 to about 4 mol carbon mol^?1 ozone by combination of ozonation with biotreatment. Simultaneously, the efficiency of removal of chlorinated guaiacols was increased by a factor of 10, which is essential for industrial application.