Ground stabilization for tunnel construction in mixed-face conditions

A scheme for providing stability measures for a tunnel excavated in mixed-ground conditions using chemical grouting is described. Typical geotechnical problems encountered during excavation are highlighted. An analytical approach for calculating the required thickness of grouted soil was developed. Grout characteristics to achieve the required behaviour are described, along with the recommended sequence of construction. A methodology employing finite element analyses to predict the tunnel behaviour during construction is proposed. It was utilized in designing the excavation support. Predictions compared well with actual field measurements.     

Field Investigation on the First Bridge Deck Slab Reinforced with Glass FRP Bars Constructed in Canada

Recently, there has been a rapid increase in using noncorrosive fiber-reinforced polymers (FRP) reinforcing bars as alternative reinforcement for bridge deck slabs, especially those in harsh environments. A new two-span girder type bridge, Cookshire-Eaton Bridge (located in the municipality of Cookshire, Quebec, Canada), was constructed with a total length of 52.08 m over two equal spans. The deck was a 200-mm-thick concrete slab continuous over four spans of 2.70 m between girders with an overhang of 1.40 m on each side. One full span of the bridge was totally reinforced using glass fiber-reinforced polymer (GFRP) bars, while the other span was reinforced with galvanized steel bars. The bridge deck was well instrumented at critical locations for internal temperature and strain data collection using fiber optic sensors. The bridge was tested for service performance using calibrated truckloads as specified by the Canadian Highway Bridge Design Code. The construction procedure and field test results under actual service conditions revealed that GFRP rebar provides very competitive performance in comparison to steel.     

Equivalent mechanical model for seismic forces in combined tanks subjected to vertical earthquake excitation

Liquid-storage tanks with circular cross sections are commonly built with a combined vessel consisting of a truncated cone and a superimposed top cylindrical cap. Unlike cylindrical tanks, combined tanks are characterized by the inclination of the walls of the conical segment. As a result, compressive meridional stresses are induced in the shell by the hydrostatic pressure of the contained fluid and the hydrodynamic pressure associated with vertical ground excitation. The current paper aims at identifying the dynamic characteristics of liquid-filled combined tanks subjected to vertical ground excitation. Numerical analysis is conducted based on a coupled finite-boundary element formulation that accounts for the associated fluid–structure interaction. An equivalent model is developed to duplicate forces induced in liquid-filled combined vessels subjected to vertical base excitation. The proposed model accounts for the flexibility of the vessel walls. Meanwhile, the contained fluid is idealized as rigid and flexible components. The proposed equivalent model provides a simplified tool to predict seismically-induced forces in liquid-filled vessels subjected to vertical earthquake excitation.     

A review on colorimetric indicators for monitoring product freshness in intelligent food packaging: Indicator dyes,preparation methods,and applications

Intelligent food packaging system exhibits enhanced communication function by providing dynamic product information to various stakeholders (e.g., consumers, retailers, distributors) in the supply chain. One example of intelligent packaging involves the use of colorimetric indicators, which when subjected to external stimuli (e.g., moisture, gas/vapor, electromagnetic radiation, temperature), display discernable color changes that can be correlated with real-time changes in product quality. This type of interactive packaging system allows continuous monitoring of product freshness during transportation, distribution, storage, and marketing phases. This review summarizes the colorimetric indicator technologies for intelligent packaging systems, emphasizing on the types of indicator dyes, preparation methods, applications in different food products, and future considerations. Both food and nonfood indicator materials integrated into various carriers (e.g., paper-based substrates, polymer films, electrospun fibers, and nanoparticles) with material properties optimized for specific applications are discussed, targeting perishable products, such as fresh meat and fishery products. Colorimetric indicators can supplement the traditional “Best Before” date label by providing real-time product quality information to the consumers and retailers, thereby not only ensuring product safety, but also promising in reducing food waste. Successful scale-up of these intelligent packaging technologies to the industrial level must consider issues related to regulatory approval, consumer acceptance, cost-effectiveness, and product compatibility.     

Correction to: An improved binary sparrow search algorithm for feature selection in data classification

Neural Computing and Applications -     

Forward osmosis desalination using pectin-coated magnetic nanoparticles as a draw solution

Clean Technologies and Environmental Policy - In this study, magnetic Fe3O4 nanoparticles and pectin-coated magnetic Fe3O4 nanoparticles were used as a potential draw solution in forward osmosis...     

PESO: Probabilistic evaluation of subspaces orthogonality for wideband DOA estimation

Multidimensional Systems and Signal Processing - This paper introduces a novel direction-of-arrival (DOA) estimation method for the closely related wideband sources. The new method estimates the...     

New sulfonated aramide nanoparticles and their copper complexes with anomalous dielectric behavior

We report the preparation of thermally stable spherical sulfonated aramides nanoparticles and their copper(II) complexes. Metal chelation with copper ions furnished polymeric complexes in a 1 : 2 ratio with square planar geometries as judged by their IR, UV, electron spin resonance, and elemental analysis data. The direct‐current electrical conductivities demonstrated the semiconducting nature of the polymeric particles and their copper complexes. Dielectric loss analysis studies showed spectral peaks appearing at characteristic frequencies, which suggested the presence of relaxing dipoles in all of the polymers. All loss peaks were shown on a linear frequency scale and appeared in the range of 1 decade, and no overlap was observed in any of the samples, whereas in the normal polymer's dielectric loss behavior, each peak covered more than 1 decade. Moreover, the peak positions did not change with increasing temperature; this indicated a nonactivated process. The reported dielectric results revealed anomalous behavior, which has not been reported before for such polymeric analogues, as the polarization in these cases was limited by nonthermal forces, and a steady‐state constant polarization was produced by an applied field. A simple method for the formation of a microporous semiconducting thin film of a polymer derived from isophthalic acid and diaminodiphenylsulfone is described. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

An experimental investigation on the use of EGR in a supercharged natural gas SI engine

The use of lean burn technology in spark-ignition engines has been dominant; however, lean burn technique can not economically satisfy the increasingly restricted future emission standards. Consequently, alternative combustion techniques need to be investigated and developed. In this paper, the use of the stoichiometric air-fuel mixture with exhaust gas recirculation (EGR) technique in a spark-ignition natural gas engine was experimentally investigated. Engine performance and NO emissions were studied for both atmospheric and supercharged inlet conditions. It was found that the use of EGR has a significant effect on NO emissions. NO emissions decreased by about 50% when EGR dilution increased from zero with an inlet pressure of 101 kPa to close to the misfire limit with an inlet pressure of 113 kPa. In addition, the use of EGR effectively suppressed abnormal combustion which occurred at higher inlet pressure. The use of higher inlet pressure in the presence of EGR improved engine performance significantly. Engine brake power increased by about 20% and engine fuel consumption decreased by about 7% while NO emissions decreased by about 12% when 5% of EGR dilution was employed with an inlet pressure of 113 kPa compared to using undiluted stoichiometric inlet mixture with an inlet pressure of 101 kPa.