Performance Evaluation of a Bluetooth-Based WLAN Adopting a Polling Protocol Under Realistic Channel Conditions

Even if Bluetooth has not been specifically designated for WLANs (Wireless Local Area Networks) and the interconnection of computers, the possibility of establishing low-cost wireless connections makes this technology attractive for this kind of context also. In this paper we assess, by means of a simulative approach that takes the complete physical and MAC level aspects into account, the performance of a Bluetooth-based WLAN adopting a roll-call polling protocol under realistic channel conditions, that is, in the presence of the typical impairments of indoor wireless communications (fading, etc); moreover, we propose an analytical formulation to derive the maximum throughput offered by a Bluetooth link and we suggest a call admission control technique based on the previous analytical considerations.     

PEG-PLA-PCL based electrospun yarns with curcumin control release property as suture

This work presents an interesting method using an electrospinning process to fabricate suture yarns loaded with curcumin to achieve reasonable mechanical properties as well as tunable drug release behavior. Different structures including different yarn counts and twists as well as core-sheath structures were used to adjust drug release properties along with improving the yarn's mechanical properties. The core parts were made of polycaprolactone and the sheath parts were made of polyethylene glycol, polylactic acid, and polycaprolactone. Drugs can be incorporated in both parts based on the required condition and application. Electrospun yarns were compared using both structural properties and their drug release profiles as metrics. The results of comparing drug release profiles of six electrospun yarns with different yarn counts and twists showed that yarns with finer fiber diameters in the core part have more drug release as well as more initial release. Overall evaluations showed that core-sheath drugloaded yarn with appropriate physical and mechanical properties can be a useful material as a drug delivery system to the site of damaged tissue. It can also be concluded that the amount and duration of drug release can be controlled using the structural parameters of electrospun yarns as an engineering tool for designing suture yarns with required properties.     

Decentralized Hierarchical Coded Caching Over Heterogeneous Wireless Networks with Multi-level Popularity Content

Wireless Personal Communications - Decentralized hierarchical coded caching is studied with two layers of caches which users receive their demands through intermediate helpers from a main server....     

Investigating the effect of custom‐made insoles and exercises on lower limb and back discomfort in assembly‐line workers in a rubber tire factory: A randomized controlled trial

Many occupations require standing for prolonged periods, which can be a major contributor to musculoskeletal problems and cause disturbances in different parts of the body, especially the lower back and lower extremities. The aim of this study was to investigate the effect of custom‐made insoles and exercise training on the lower limb and lower back discomfort in workers on a production line at a rubber tire factory. One hundred male workers (mean age 35.96 years, work experience of 10.62 years, standing time 6.58 hr) participated in this randomized controlled trial. The men were randomly assigned to one of four groups: (a) custom‐made insole plus lower limb exercises, (b) insoles only, (c) lower limb exercises only, and (d) no intervention. Discomfort level was recorded with a visual analog scale and a body map. The data were analyzed with analysis of covariance. The results showed a significant difference in discomfort levels between groups in the lower back (p = .001), thigh (p = .001), and knee (p = .001) areas. The combined insole and exercise group had less discomfort in the lower back, thigh, and knee. In the group that used the insole only without exercises, the discomfort level in the lower back area was reduced. The results indicate that the simultaneous use of insoles and exercises might be an effective intervention to reduce discomfort in the lower limbs and lower back in workers who remain standing for prolonged periods.     

Optimization of Run-of-River Hydropower Plant Design under Climate Change Conditions

The assessment of climate change and its impacts on hydropower generation is a complex issue. This paper evaluates the application of representative concentration pathways (RCPs, 2.6, 4.5, and 8.5) with the change factor (CF) method and the statistical downscaling method (SDSM) to generate six climatic scenarios of monthly temperature and rainfall over the period 2020–2049 in the Karkheh basin, Iran. The identification of unit hydrographs and component flows from rainfall, evaporation and streamflow data (IHACRES) model was employed to simulate runoff for the purpose of designing a run-of-river hydropower plant in the Karkheh basin. The non-dominated sorting genetic algorithm (NSGA)-II was employed to maximize yearly energy generation and the plant factor, simultaneously. Results indicate the runoff scenarios associated with the SDSM lead to higher run-of-river hydropower generation in 2020–2049 compared to the CF results.     

Effective gas separation through graphene oxide containing mixed matrix membranes

In the present study, graphene oxide (GO) was incorporated into poly(vinylidene fluoride) (PVDF) and chemically modified PVDF (M‐PVDF) to prepare mixed matrix membranes (MMMs) for gas separation application. Performed analyses proved appropriate dispersion of exfoliated GO sheets in polymer matrices and sufficient compatibility at the interfacial phases. M‐PVDF based MMMs were thermally and mechanically more stable relative to the PVDF‐based MMMs. The oxygen containing functional groups in M‐PVDF was probably the main reason for this more stability. PVDF/GO MMMs rendered low gas permeability and high selectivity. Both impermeable GO sheets and crystalline phases of PVDF were responsible for such behavior. On the other hand, interestingly gas permeability of M‐PVDF/GO MMMs was enhanced while no substantial decline was recorded in gas selectivity. For instance, He and CO₂ permeability was increased 12.46% and 25.89%, respectively, compared to the pure PVDF membrane. This behavior originated from functional groups of M‐PVDF and the interaction of these groups with GO sheets. Since GO often amplified gas barrier properties of polymers, such increscent would be appreciable. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46271.     

Optimal SMDP‐Based Connection Admission Control Mechanism in Cognitive Radio Sensor Networks

Traffic management is a highly beneficial mechanism for satisfying quality‐of‐service requirements and overcoming the resource scarcity problems in networks. This paper introduces an optimal connection admission control mechanism to decrease the packet loss ratio and end‐to‐end delay in cognitive radio sensor networks (CRSNs). This mechanism admits data flows based on the value of information sent by the sensor nodes, the network state, and the estimated required resources of the data flows. The number of required channels of each data flow is estimated using a proposed formula that is inspired by a graph coloring approach. The proposed admission control mechanism is formulated as a semi‐Markov decision process and a linear programming problem is derived to obtain the optimal admission control policy for obtaining the maximum reward. Simulation results demonstrate that the proposed mechanism outperforms a recently proposed admission control mechanism in CRSNs.     

A microwave-assisted new synthesis of sulfonylidene–sulfonamide via reactions of N-sulfonylketenimine and sodium arylsulfinates

A rapid practical microwave-assisted new synthesis of sulfonylidene–sulfonamide was developed via the one-pot, three-component reaction of sulfonyl azides, terminal alkynes, and sodium arylsulfinates catalyzed by copper(I) iodide in DMF in moderate to good yields.