Modified toughness used to evaluate the effect of polymer modified asphalt on SMA

Abstract

Toughness, as defined in ASTM D5801, is the work used to stretch a specimen until fracture, and is used to evaluate the ability of polymer modified asphalt (PMA) to resist deformation. Fracture elongations in PMA are usually longer than 10 cm. However, it is almost impossible for asphalt concrete, with or without PMA, to endure such large deformation before fracture. It is presumed that an effective elongation exists for more effective determination of toughness. Principle component analysis (PCA) and single regression analysis were used in this study to evaluate the correlation between physical tests of PMA, including toughness and performance tests of Stonic Mastic Asphalt (SMA). Meanwhile, performance tests, including resilient modulus tests, creep tests and indirect tensile tests, were conducted on SMA samples. According to the results form Principle Components Analysis (PCA), it was observed that only a common factor affects the performance tests. Regression analyses were used to find common factors from physical tests of PMA. Correlation coefficients between toughness and performance tests were found to be better than other physical tests. When toughness was calculated with effective elongation (6.5 cm), R ² was 0.90. In our opinion, the desirable PMA should provide SMA enough work to resist the deformation while the deformation is still small. This result was also confirmed by observation of SEM and Rheological analysis. Modified toughness (calculated with effective elongation) considered as the common factor, is a simple method to evaluate the microstructure of PMA. Overall, modified toughness seems promising for use in evaluation of the effect of PMA on SMA.     

Shaking table test and verification of development of an accumulated semi-active hydraulic damper as an active interaction control device

Semi-active control is based on the use of the emerging concept of active control and passive control. The developed accumulator semi-active hydraulic damper (ASHD) is converted to interaction element (IE) of active interaction control (AIC). Systemic equations of motion, control law and control rulers of this proposed new AIC are studied in this research. A full-scale multiple degrees of freedom shaking table is tested to verify the energy dissipation of this proposed AIC, including test building without control, with passive control added involving various stiffness ratios and also with synchronic control added involving various stiffness ratios. Shock absorption of displacement can be up to 74–81% of that of the test structure with stiffness ratio = 2.3387 and 1.790 at 1st and 2nd floor under control of synchronous switch of this proposed AIC, respectively. No matter what the test structure added with various stiffeners at 1st and 2nd floor under synchronous control, test results of shock absorption ratio of acceleration show good seismic proof capability. In addition, base shear control effects of this proposed AIC method are higher than those of the test structure with various stiffeners added under passive control. These results show that AIC with stiffeners for structural control provides the characteristics of a stabilized structure under excitation of near-fault earthquake with velocity impulse action.     

Emission of polycyclic aromatic hydrocarbons from the pyrolysis of liquid crystal wastes

A liquid crystal display can be described as a panel consisting of two plates of glass with liquid crystals in the space between. Generally, the liquid crystal wastes are extracted and separated into various fractions. Some recyclable materials, i.e., metals, glass, plastics, etc., are recycled, but the liquid crystals are incinerated. The emission factors for 16 U.S. EPA priority polycyclic aromatic hydrocarbons (PAHs) from the combustion of liquid crystal are approximately 390 and 1520 times higher than that of waste terephthalic acid and biological sludge combustion, respectively. In this study, we determined the emission of PAHs from the liquid crystals pyrolysis. We also investigated the fragments and gas compositions using on-line thermogravimetry–mass spectrometry (TG–MS). A temperature series of 14 fragments was analyzed in nitrogen, and was found to include m/z: 30, 32, 42, 44, 55, 57, 67, 81, 95, 109, 128, 166, 178, and 202. The fragments at m/z 32 represents formaldehyde and the fragment at m/z 44 is carbon dioxide. The fragments at m/z 55, 57, 67, 81, 95, and 109 represent hydrocarbon components, all of which may be liquid crystal by products. The TG–MS as analyzed above can offer a better understanding of the mechanisms of byproduct formation in liquid crystal waste pyrolysis.Experimentally, not detected (n.d.) −5.98 and n.d. −20.2 μg/g of 16 PAHs, in the particulate and gas phases, respectively, are determined from the emission of liquid crystal waste pyrolysis. The PAH profiles showed a predominance of naphthalene (42.6%) and phenanthrene (13.5%). The total PAH emissions for the 16 species were 7.75 and 44.05 μg/g in the particulate and gas phases, respectively, significantly lower than the values associated with liquid crystal combustion. From the viewpoint of PAH emission control, our results suggest that the pyrolysis is a better option for the disposal of liquid crystal wastes than that of combustion.     

A label‐based information flow control model for object‐oriented systems

Abstract

This paper proposes a label‐based information flow control model to prevent information leakage within object‐oriented systems. It offers the features of: (a) adapting to dynamic object state change, (b) adapting to dynamic role change, (c) preventing indirect information leakage, (d) detailing the control granularity to variables, (e) allowing purpose‐oriented method invocation, (f) controlling method invocation through argument sensitivity, (g) allowing declassification, and (h) allowing only trusted sources to write a variable.     

Construction rescheduling based on a manufacturing rescheduling framework

Changes during project execution frequently require schedule updating and rescheduling. However, few studies have discussed rescheduling issues or implemented rescheduling solutions for construction projects. This study investigates resource-constrained construction rescheduling issues using concepts associated with manufacturing rescheduling. Based on an initial schedule and actual progress, a novel rescheduling optimization model using Constraint Programming (CP) techniques is developed to reschedule projects. Two rescheduling methods: (1) complete regeneration (CR); and, (2) partial rescheduling (PR) while minimizing overall project variation are implemented in the proposed model to demonstrate the model capability and applications. PR requiring additional treatments to decrease overall project variation is performed using a novel constraint-release mechanism. Finally, using a case study, optimization results obtained using two rescheduling methods are analyzed and discussed.     

Novel impacts of glycol-modified poly(ethylene terephthalate)(PETG) to crystallization behavior of polyethylene naphthalate (PEN) within stretched miscible blends

For studied blends of amorphous glycol-modified poly(ethylene terephthalate) (PETG) and semicrystalline polyethylene naphthalate (PEN), melt miscibility is understood from the linear variation of a single glass transition temperature (T_g) over the entire composition range. The diluent effect of PETG component severely retarded the crystallization of PEN component within blends. Nevertheless, after being through isothermal stretching at 120 °C, crystallization was able to progress efficiently during heating in a continuous manner. Instead of being thermally relaxed back to amorphous state, parallel sliding motions of stretched PEN segments toward crystallization appear rather dominant. Within stretched blends, the PETG content emerged as a critical factor to the crystallinity increase of PEN fraction and the absence of lattice defect, instead of behaving as a diluent component. Furthermore, as being indicated by in-situ small-angle X-ray experiments, regular lamellar stacking gradually developed within stretched blends through heating, which indicates the involvement of thermally activated self-association of randomly distributed crystalline lamellae. With including a higher fraction of PETG component, these secondary ordering processes including lamellar thickening can be activated at lower temperature. Hence, the accompanied thermal relaxation of flexible PETG segment is inferred able to lubricate the sliding of stretched PEN segments in amorphous regions via lowering encountered frictional hindrance, and thus enhance both primary and secondary ordering processes within stretched blends.