GOP-SDN: an enhanced load balancing method based on genetic and optimized particle swarm optimization algorithm in distributed SDNs

Wireless Networks - One of the biggest challenges of distributed software defined networks (SDNs) is to create load balancing on controllers to reduce response time. Although recent studies have...     

A biochar from casein and its properties

A biochar was prepared by pyrolysis of casein. A helium and mercury porosimeter were used to measure the true and apparent densities of the chars respectively, elemental and IR analysis were used to characterize the chemical composition of char. A SEM was used to observe the char surfaces in order to verify the presence of porosity. The biochar has 9.02% of nitrogen, content of porosity is 20%. The experimental results show that it is possible to prepare chars with relatively high porosity from casein for the further preparation of activated carbon.     

Qualitative characteristics of power-generating coals from some deposits in Mongolia

The results of a study of the chemical composition and technological properties of coals from the Khar Tarvagatai, Nuurst Khotgor, and Khushuut deposits are presented in this article.     

Delay times in Si MOSFETS in the 4.2–400 K temperature range

Temperature dependence of propagation delay time and power-delay product in Si MOSFETs (fabricated using 1 μm X-ray lithography) has been measured using 19-stage ring oscillators. The delay time was found to decrease with lowering temperature. As a numerical example we found that a delay time of 30 ps at room temperature decreased to 22 and 18 ps at 77 and 4.2 K respectively, and increased to 38 at 400 K. The power showed a slight increase with decreasing temperature, while the power-delay product decreased. The decrease in the delay time has been explained in terms of increase in the electron drift velocity with decreasing temperature, as well as decrease in one component of the capacitive load, namely the source-drain junction capacitance, due to carrier freeze-out.     

Physicochemical characteristics of adsorbents based on coals from the Khar Tarvagatai deposit in Mongolia

The results of a study of the physicochemical characteristics of porous carbon materials prepared based on low-metamorphosed black coal from the Khar Tarvagatai deposit in Mongolia are presented in this article. The carbon material synthesized with the use of an alkaline impregnation method corresponds to uniformly porous, predominantly, microporous (to 70% of micropores in terms of adsorption volume) sorbents with a specific surface area of ～1100 m²/g. The use of additional ozonolytic activation of the sorbent facilitated an insignificant decrease in its porosity with an increase in the number of oxygen groups on the sample surface by a factor of 2.5 in this case.     

Load‐balanced data gathering in Internet of Things using an energy‐aware cuckoo‐search algorithm

This paper deals with the lifetime problem in the Internet of Things. We first propose an efficient cluster‐based scheme named “Cuckoo‐search Clustering with Two‐hop Routing Tree (CC‐TRT)” to develop a two‐hop load‐balanced data aggregation routing tree in the network. CC‐TRT uses a modified energy‐aware cuckoo‐search algorithm to fairly select the best cluster head (CH) for each cluster. The applied cuckoo‐search algorithm makes the CH role to rotate between different sensors round by round. Subsequently, we extend the CC‐TRT scheme to present two methods for constructing multi‐hop data aggregation routing trees, named “Cuckoo‐search Clustering with Multi‐Hop Routing Tree (CC‐MRT)” and “Cuckoo‐search Clustering with Weighted Multi‐hop Routing Tree (CC‐WMRT).” Both CC‐MRT and CC‐WMRT rely on a two‐level structure; they not only use an energy‐aware cuckoo‐search algorithm to fairly select the best CHs but also adopt a load‐balanced high‐level routing tree to route the aggregated data of CHs to the sink node. However, CC‐WMRT slightly has a better performance thanks to its low‐level routing strategy. As an advantage, the proposed schemes balance the energy consumption among different sensors. Numerical results show the efficiency of the CC‐TRT, CC‐MRT, and CC‐WMRT algorithms in terms of the number of transmissions, remaining energy, energy consumption variance, and network lifetime.     

Remanufacturing and energy savings

Remanufactured products that can substitute for new products are generally claimed to save energy. These claims are made from studies that look mainly at the differences in materials production and manufacturing. However, when the use phase is included, the situation can change radically. In this Article, 25 case studies for eight different product categories were studied, including: (1) furniture, (2) clothing, (3) computers, (4) electric motors, (5) tires, (6) appliances, (7) engines, and (8) toner cartridges. For most of these products, the use phase energy dominates that for materials production and manufacturing combined. As a result, small changes in use phase efficiency can overwhelm the claimed savings from materials production and manufacturing. These use phase energy changes are primarily due to efficiency improvements in new products, and efficiency degradation in remanufactured products. For those products with no, or an unchanging, use phase energy requirement, remanufacturing can save energy. For the 25 cases, we found that 8 cases clearly saved energy, 6 did not, and 11 were too close to call. In some cases, we could examine how the energy savings potential of remanufacturing has changed over time. Specifically, during times of significant improvements in energy efficiency, remanufacturing would often not save energy. A general design trend seems to be to add power to a previously unpowered product, and then to improve on the energy efficiency of the product over time. These trends tend to undermine the energy savings potential of remanufacturing.     

Recrystallization of polysilicon films using incoherent light

A novel system has been designed and constructed for recrystallization of polysilicon films. This system utilizes tungsten light sources to heat, zone melt and subsequently crystallize polysilicon films on insulating substrates. The system has been successfully used to crystallize 0.5 μm polysilicon films deposited on 0.5 μm SiO₂₁ grown on three inch Si wafers. Initial results are presented.     

Interference-aware multicast and broadcast routing in wireless mesh networks using both rate and channel diversity

This paper deals with the problem of load-balanced routing in multi-radio multi-rate multi-channel wireless mesh networks. Our analysis relies on the multicast and broadcast sessions, where each session has a specific bandwidth requirement. We show that using both rate and channel diversity significantly improves the network performance. Toward this goal, we propose two cross-layer algorithms named the “Interference- and Rate-aware Multicast Tree (IRMT)” and the “Interference- and Rate-aware Broadcast Tree (IRBT)”. The proposed algorithms jointly address the problems of routing tree construction, transmission channel selection, transmission rate selection, and call admission control. As an advantage, the IRMT and the IRBT algorithms consider both inter-flow and intra-flow interference. These schemes not only improve the utilization of the network resources, but also balance the traffic load over the network. Numerical results demonstrate the efficiency of the proposed algorithms in terms of the number of transmissions, the load-balancing, and the network throughput.