A comparative study on pyrolysis reactivity and gas release characteristics of biomass and coal using TG-MS analysis

Pyrolysis reactivity and gas release characteristics of biomass and coals were comparatively investigated using TG-MS. In addition, chemical compositions and structures of tested samples were determined to correlate pyrolysis gas release characteristic. It was found that pyrolysis reactivity and gaseous product release were hardly varied with pyrolysis heating rate. Furthermore, pyrolysis rates of two biomass samples were greater than those of coals, which were mainly attributed to the chemical compositions and the gaseous product evolution process. The result also showed that gaseous product release during pyrolysis process was related to the presence of different functional groups in samples.     

Texting While Driving: An Empirical Investigation of Students’ Attitudes and Behaviors

The distracting effects of texting while driving activity of young adults are receiving increasing attention. The findings indicate that individuals involved in texting while driving also engage in other risky behaviors. Furthermore, frequency of texting while driving appears to be related to several factors, including self-control, attitudes toward texting and responsible driving, and opinions of peers, but interestingly not with social responsibility. In conclusion, the frequency of texting while driving of young adults appears to be related to several factors, suggesting possible ways the frequency of texting while driving may be affected.     

A field study of human factors and vehicle performance associated with PHEV adaptation

Smart-grid and electric-vehicle technologies are rapidly diffusing, yet important policy implications remain to be fully analyzed. This multi-year field study sought to fill part of this gap by exploring human adaptation to plug-in hybrid electric vehicle (PHEV) performance and vehicle charging in smart-grid environments. Homes were equipped with smart meters in a smart-grid experiment conducted by the local utility. Study households were organized by either standard or time-of-use electricity pricing, and randomly assigned to “managed” or “unmanaged” charging scenarios. Using a mixed-methods approach, study data were collected through vehicle data loggers, smart-plugs interviews, and questionnaires. The paper describes vehicle operations and performance; the ways in which households managed PHEV charging; and the manner in which they responded to smart-grid, smart-plug, and dashboard feedback. Findings indicate that households actively managed PHEV charging; however, they preferred flexible charging scenarios. Charging-management decisions were influenced by electricity-pricing. Online feedback on household- and vehicle-electricity consumption was generally ignored, but drivers responded to dashboard feedback as they drove. These results provide empirical bases for government and corporate policymakers to improve policy decisions relative to PHEV impacts on electricity loads, design of smart-grid feedback, and design of charging infrastructures.     

Microstructure evolution and mechanical properties of thermally sprayed coating modified by laser remelting and injection with tungsten carbide

The forming quality of thermally sprayed coatings is often severely impacted by inherent defects, including porosity, microcracks, and mechanical bonding. The poor adhesive strength hinders the utilization of thermal spray technology when fabricating ceramic-reinforced metal matrix composite coatings (MMCCs). Thus, in this study, a negative defocus laser remelting and injection method (LRI) is introduced to modify a thermally sprayed coating with WC ceramics. The microstructure and mechanical property (microhardness, elastic modulus, and wear resistance) evolution of a LRI-modified WC reinforced composite coating is systematically characterized and compared with that for an as-sprayed coating. The LRI method is proven to improve the inherent defects of the initial coating and avoid severe reactions and dissolution of reinforced particles at high temperatures, and can be used to form a high-quality composite coating with a maximum strengthening effect of the ceramic particles. Compared with the initial coating, the elastic modulus and microhardness of the LRI coating are increased by 57.22% and 111.06%, respectively, whereas the abrasion rate is decreased by 54.33%.     

Tribological Properties of Functionalized Ionic Liquids Containing Ester-group as Lubricants for Steel-Steel System

A series of functionalized ionic liquids (ILs) containing ester-group were synthesized and their tribological properties as lubricants for steel-steel contact were studied and compared with a non-functionalized ionic liquid and perfluoropolyethers (PFPE). The morphology and chemical composition of the worn scars were analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively, and the possible lubrication mechanism of ILs was discussed. As a result, all ILs demonstrated a better lubricity and a much higher load-carrying capacity than PFPE used as lubricants for the steel-steel tribomates system. The functionalized ILs with ester-group showed slightly worse friction reducing ability than their nonfunctionalized counterparts at relatively lower loads owing to their higher viscosity, but then exhibited better antiwear ability because the ester group they contained had not only physical but also strong chemical reactions with the freshly exposed steel surface and formed chemical adsorption boundary films on the worn surface during friction process. Under high loads, some tribochemical reactions took place between the active elements, such as fluorine which were released from the ILs, and fresh metal surfaces of rubbing pairs to form the admixture reaction films, which were mainly composed of ferric fluoride mixed with ferric oxide, leading to lower friction coefficients and good wear resistance.     

Alginate gel particles–A review of production techniques and physical properties

The application of hydrocolloid gel particles is potentially useful in food, chemical, and pharmaceutical industries. Alginate gel particles are one of the more commonly used hydrocolloid gel particles due to them being biocompatible, nontoxic, biodegradable, cheap, and simple to produce. They are particularly valued for their application in encapsulation. Encapsulation in alginate gel particles confers protective benefits to cells, DNA, nutrients, and microbes. Slow release of flavors, minerals, and drugs can also be achieved by encapsulation in gel particles. The particle size and shape of the gel particles are crucial for specific applications. In this review, current methods of producing alginate gel particles will be discussed, taking into account their advantages, disadvantages, scalability, and impact on particle size. The physical properties of alginate gel particles will determine the effectiveness in different application conditions. This review will cover the current understanding of the alginate biopolymer, gelation mechanisms and factors affecting release properties, gel strength, and rheology of the alginate gel particle systems.     

Experimental and numerical study of oblique impact on woven composite sandwich structure: Influence of the firing axis orientation

During flight, aircrafts can be submitted to complex loadings. The reliability of their structure is an essential aspect in ensuring passenger safety. In the specific case of helicopters, blades are subjected to impact loading. The following work will focus on the experimental and numerical study of an oblique impact on the skin of the blade. It is equivalent in a first approach to an impact on a sandwich panel comprising a foam core and a thin woven composite skin. This study aims to identify the mechanisms of damage to the skin for different orientations of the firing axis, and to develop a representative model of the damage kinetics adapted to the modeling of the complete structure. Thus, an F.E. semi-continuous explicit model has been developed. It relies on the development of a specific damageable element at the woven mesh scale. Numerical results obtained are accurate, allowing the identification of the damage mechanism of the woven skin for different firing orientations.     

Wear behaviour of steel coatings produced by friction surfacing

Friction surfacing was performed to produce multi-layer coatings of AISI 1024, AISI 1045 and AISI H13 over mild steel substrates where a continuous joining was achieved between adjacent layers and between the clad and the substrate. Microscopic and hardness characterization revealed the presence of bainitic and martensitic microstructures which influenced the hardness of the coatings. The study aimed to determine which material combination was more wear-resistant. The analysis suggested that AISI 1024 presents the least wear, both in terms of friction coefficient and wear rate. This is due to the formation of adherent protective oxide layer which is not present in both the AISI 1045 and AISI H13 steels.     

Combined effects of fiber/matrix interface and water absorption on the tribological behaviors of water-lubricated polytetrafluoroethylene-based composites reinforced with carbon and basalt fibers

Tribological behaviors of two PTFE-based composites reinforced with carbon fibers and basalt fibers sliding against stainless steel under water lubrication were investigated and compared with those of pure PTFE. Results showed that carbon fibers were well bonded with PTFE matrix by dendritic PTFE nano-ribbons in a Boston ivy-like manner, but the basalt fibers were poorly bonded with the matrix. Due to the great accelerating effect of poor fiber/matrix interfacial adhesion on water absorption, BF/PTFE with the highest crystallinity unexpectedly showed the highest water absorption, resulting in serious matrix plasticization and degradation of fiber/matrix interfacial adhesion. As a result, as the reinforcement failure of basalt fibers occurred, BF/PTFE exhibited the highest wear rate. Instead, because good fiber/matrix interfacial adhesion was favor of the resistance to water intrusion, CF/PTFE composite was not dominated by remarkable matrix plasticization and fiber/matrix interface degradation, and showed the lowest wear rate.     

The Synthesis and Characterization of a Clean Hydrofracturing Fluid

Abstract

Surfactant-based fracturing gels are considered as clean gels due to the absence of insoluble residues after hydraulic fracturing of tight reservoir. Conventionally used highly viscous polymer gels damage the formation by blocking the fluid path in a fractured formation. The present work has been accomplished with the purpose of evaluating an anionic surfactant-based gel for hydraulic fracturing. Rheological properties and proppant carrying capacity of the synthesized gel were studied as a function of shear rate, temperature, and pH, which affect the gel behavior at the downhole. Proppant carrying capacity was also reported with varying proppant loadings. Rheological properties and proppant carrying capacity of synthesized gel were compared with conventionally used guar gel.