Selective CO2 Capture and High Proton Conductivity of a Functional Star‐of‐David Catenane Metal–Organic Framework

Network structures based on Star‐of‐David catenanes with multiple superior functionalities have been so far elusive, although numerous topologically interesting networks are synthesized. Here, a metal–organic framework featuring fused Star‐of‐David catenanes is reported. Two triangular metallacycles with opposite handedness are triply intertwined forming a Star‐of‐David catenane. Each catenane fuses with its six neighbors to generate a porous twofold intercatenated gyroid framework. The compound possesses exceptional stability and exhibits multiple functionalities including highly selective CO₂ capture, high proton conductivity, and coexistence of slow magnetic relaxation and long‐range ordering.     

Joint spectrum sensing and resource allocation optimization using genetic algorithm for frequency hopping–based cognitive radio networks

In cognitive radio (CR) networks, secondary users should effectively use unused licensed spectrums, unless they cause any harmful interference to the primary users. Therefore, spectrum sensing and channel resource allocation are the 2 main functionalities of CR networks, which play important roles in the performance of a CR system. To maximize the CR system utility, we propose a joint out‐of‐band spectrum sensing and operating channel allocation scheme based on genetic algorithm for frequency hopping–based CR networks. In this paper, to effectively sense the primary signal on hopping channels at each hopping slot time, a set of member nodes sense the next hopping channel, which is called out‐of‐band sensing. To achieve collision‐free cooperative sensing reporting, the next channel detection notification mechanism is presented. Using genetic algorithm, the optimum sensing and data transmission schedules are derived. It selects a sensing node set that participate the spectrum sensing for the next expected hopping channel during the current channel hopping time and another set of nodes that take opportunity for transmitting data on the current hopping channel. The optimum channel allocation is performed in accordance with each node's individual traffic demand. Simulation results show that the proposed scheme can achieve reliable spectrum sensing and efficient channel allocation.     

Management of price uncertainty in short-term generation planning

Price uncertainty is faced by gencos in the scheduling of their units in competitive power markets. the proper way to deal with the uncertainty depends on the risk preference of the genco. two important means to manage the price uncertainty are (i) suitable flexible bids and (ii) the use of hedging tools such as forward contracts. the influence of these factors in the genco's short-term generation planning and the corresponding profit performances is studied. the market price is represented by lognormal distribution, genco risk behaviour is represented by exponential utility functions, the bid functions are taken to be flexible and simple contracts for hedging are assumed available. the unit commitment problem is combined with the hedging problem to obtain the optimal solution. formulation of the problem to maximise profit in the spot market and its extension to incorporate the risk behaviour of the gencos and the forward contacts for hedging is presented. solution method based on genetic algorithms is implemented in matlab. it is observed through numerical examples that the flexible outputs and the forward contracts can be used to hedge against price risks to achieve desired profit performance according to gencos' risk behaviour.     

Environmental emission mitigation potential of efficient electrical appliances in Sri Lanka

This study assesses the techno-economic potential of selected efficient demand-side appliances to mitigate emission of air pollutants from the power sector of Sri Lanka. The study shows that through the use of the selected efficient appliances a total of about 38 646 GWh (i.e. 18·5% of total electricity generation) and about 25·6% (29 541, 000 tons), 34·2% (293,000 tons) and 34·6% (374,000 tons) of the total CO₂, SO₂ and NO_x emission respectively could be avoided during 1997–2015 with the use of the efficient appliances from the technical and national economic perspectives. The generation savings from utility and user perspectives and emission mitigation potential are, however, significantly smaller as all the selected appliances are not found cost effective from these perspectives. This is mainly because electricity prices in the commercial and industrial sectors exceed the corresponding long-run marginal cost (LRMC) of electricity supply. © 1998 John Wiley & Sons, Ltd.     

Creep deformation behavior of Sn–Zn solder alloys

Creep properties of three Sn–Zn solder alloys (Sn–9Zn, Sn–20Zn, and Sn–25Zn, wt%) were studied using the impression creep technique. Microstructural characteristics were examined using a scanning electron microscope. The alloys exhibited stress exponents of about 5.0. The activation energy for creep was calculated to be ~50–75 kJ/mol with a mean value of 66.3 kJ/mol. The likely creep mechanism was identified to be the low temperature viscous glide of dislocations.     

Highly Efficient Rapid Annealing of Thin Polar Polymer Film Ferroelectric Devices at Sub‐Glass Transition Temperature

An unexpected rapid anneal of electrically active defects in an ultrathin (15.5 nm) polar polyimide film at and below glass transition temperature (T_g) is reported. The polar polymer is the gate dielectric of a thin‐film‐transistor. Gate leakage current density (J_g) through the polymer initially increases with temperature, as expected, but decreases rapidly at T_g ? 60 °C. After ≈2 min at T_g, the leakage is reduced by nearly three orders of magnitude. A concomitant observation is that the drain current (I_d)–gate voltage (V_g) hysteresis decreases with temperature, reaching zero at nearly the same temperature at which J_g collapses. As J_g drops further, the drain current hysteresis increases again but in the opposite direction. This combination strongly supports the interpretation of rapid defect annealing.     

Electro ultrasonic remediation of polycyclic aromatic hydrocarbons from contaminated soil

The polycyclic aromatic hydrocarbons (PAHs) with high molecular mass are renown for their high persistence in the soil, hydrophobic and toxicity. Remediation of these pollutants is still an unsolved task and needs more researches to be performed. The coupling of electrokinetics (EK) with ultrasonic energy (US) has advantages on desorbing and migrating PAHs from contaminated soil. US and EK work together to destroy PAHs. The objective of this study was to treat PAHs contaminated soil by using EK and ultrasonication. The contaminated oil contained about 100 mg kg⁻¹ chrysene. Experiments with US, EK and combined EK and ultrasound were conducted in reactors and pans with and without iron anodes. Results indicated that the removal was more effective with lower concentrations of chrysene. The average removal was better in experiment with combined EK and ultrasound using iron anode. This might be due to increase in electroconductivity by iron ions.     

BIM adoption by public facility agencies: impacts on occupant value

ABSTRACT

Many governments have begun to demand that large public facility agencies adopt and implement building information modelling (BIM) in their business processes. Some have published BIM guides. Most of these are technical specifications that are useful at the project level, but they provide no support for the organization-level adoption effort. On the basis of a literature review, action research and case studies of five large UK government facility agencies, a BIM adoption impact map (BIM AIM) is proposed. It describes a set of possible relationships between the actions taken by public facility agencies, the intermediate outcomes of their actions and the eventual achievement of value for the occupants of the facilities they build. BIM AIM can be used by public facility agencies with a wide variety of construction project types to analyse and visualize the strengths, weaknesses and opportunities in their BIM adoption efforts, potentially enabling them to focus on social impacts and outcomes rather than on the technological or management actions that intermediate stakeholders promote.