FRP confined concrete columns: Behaviour under extreme conditions

The behaviour of concrete columns wrapped with fibre reinforced polymer (FRP) materials when exposed to several extreme conditions is evaluated. Cold regions environments, FRP repair of corroding reinforced concrete columns, and fire resistance are all considered. For the cold regions exposure, FRP wrapped cylinders (152 × 305 mm) are exposed to temperatures as low as −40 °C or to up to 300 cycles of freeze-thaw (−18 °C to +15 °C). The combination of freeze-thaw exposure with sustained loading is also examined. For FRP wrapping of corroding reinforced concrete columns, the results of tests on cylinders and larger-scale circular columns (300 × 1200 mm) are presented. The specimens are corroded and then wrapped with FRP sheets. The rate of corrosion is monitored both before and after wrapping. The final extreme condition that is considered is fire exposure. Tests on full-scale reinforced concrete columns (400 × 3800 mm) exposed to a standard fire are described and discussed. Overall, the results demonstrate that FRP confined concrete columns tested in concentric axial compression have adequate performance under several extreme conditions such as low temperature, freeze-thaw action, corrosion of internal reinforcement, and fire exposure.     

Message Effects and Social Determinants of Health: Its Application to Cancer Disparities

Recent work on message effects theories offers a fruitful way to systematically explore how features, formats, structures of messages may attract audience attention and influence the audience and is of great relevance to public health communications. Much of this work, however, has been pursued primarily at the individual level of analysis. It is our contention that message effects on health outcomes could potentially be moderated and mediated by social contextual factors in public health such as social class, social organizations and neighborhoods among others, leading to differential effects among different audience sub-groups. This essay, through a selective review of literatures in communication and social epidemiology, will explore how major message effects may moderate and mediate the role of social determinants of health on cancer control, specifically cancer-related health disparities.     

Exploiting Object Escape and Locking Information in Partial-Order Reductions for Concurrent Object-Oriented Programs

Explicit-state model checking tools often incorporate partial-order reductions to reduce the number of system states explored (and thus the time and memory required) for verification. As model checking techniques are scaled up to software systems, it is important to develop and assess partial-order reduction strategies that are effective for addressing the complex structures found in software and for reducing the tremendous cost of model checking software systems. In this paper, we consider a number of reduction strategies for model checking concurrent object-oriented software. We investigate a range of techniques that have been proposed in the literature, improve on those in several ways, and develop five novel reduction techniques that advance the state of the art in partial-order reduction for concurrent object-oriented systems. These reduction strategies are based on (a) detecting heap objects that are thread-local (i.e., can be accessed by a single thread) and (b) exploiting information about patterns of lock-acquisition and release in a program (building on previous work). We present empirical results that demonstrate upwards of a hundred fold reduction in both space and time over existing approaches to model checking concurrent Java programs. In addition to validating their effectiveness, we prove that the reductions preserve LTL_?X properties and describe an implementation architecture that allows them to be easily incorporated into existing explicit-state software model checkers.     

3D Printing All‐Aromatic Polyimides using Mask‐Projection Stereolithography: Processing the Nonprocessable

High‐performance, all‐aromatic, insoluble, engineering thermoplastic polyimides, such as pyromellitic dianhydride and 4,4′‐oxydianiline (PMDA–ODA) (Kapton), exhibit exceptional thermal stability (up to ≈600 °C) and mechanical properties (Young's modulus exceeding 2 GPa). However, their thermal resistance, which is a consequence of the all‐aromatic molecular structure, prohibits processing using conventional techniques. Previous reports describe an energy‐intensive sintering technique as an alternative technique for processing polyimides with limited resolution and part fidelity. This study demonstrates the unprecedented 3D printing of PMDA–ODA using mask‐projection stereolithography, and the preparation of high‐resolution 3D structures without sacrificing bulk material properties. Synthesis of a soluble precursor polymer containing photo‐crosslinkable acrylate groups enables light‐induced, chemical crosslinking for spatial control in the gel state. Postprinting thermal treatment transforms the crosslinked precursor polymer to PMDA–ODA. The dimensional shrinkage is isotropic, and postprocessing preserves geometric integrity. Furthermore, large‐area mask‐projection scanning stereolithography demonstrates the scalability of 3D structures. These unique high‐performance 3D structures offer potential in fields ranging from water filtration and gas separation to automotive and aerospace technologies.     

In situ nanomechanical behaviour of coexisting insulating and metallic domains in VO<Subscript>2</Subscript> microbeams

Measuring the electrical and mechanical responses of coexisting phases at nanoscale provides a platform to engineer micro-/nanoscale pattern of metallic and insulating domains with control over properties to make novel devices. Here, we employ several in situ characterization techniques, namely Raman, optical imaging and electrical measurements, to identify the phase coexistence of metallic and insulating domains. Further, we performed site-specific in situ nanoindentation to address the spatial variation in nanomechanical properties in vanadium dioxide (VO₂) single-crystal microbeams in proximity to metal–insulator transition temperature. We also investigated load or contact depth dependence on elastic modulus at various temperatures to avoid the interference of indentation size effect on nanomechanical properties across the phase transition. The obtained results confirm the abrupt increase in elastic modulus (~17 GPa) and nanohardness (1 GPa) across the transition from monoclinic (insulator) to rutile (metal) phase.     

A Novel Approach: Hydrothermal Method of Fine Stabilized Superparamagnetics of Cobalt Ferrite (CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript>) Nanoparticles

Spinel CoFe₂O₄ nanoparticles were synthesized by a simple, economical, and eco-friendly hydrothermal method (HM) using metal nitrates and polyvinyl pyrrolidone. The structural, morphological, and magnetic properties of the products were determined and characterized in detail by X-ray diffraction (XRD), high-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray spectroscopy (EDX), photoluminescence (PL) spectroscopy, vibrating sample magnetometry (VSM), and Brunauer–Emmett–Teller (BET) surface area analysis. Key parameters influencing the structural performance, such as particle size and shape, annealing temperature, functionalization, and magnetic properties, have been comprehensively discussed. The effect of the catalyst and solvent on the catalytic oxidation of benzyl alcohol using the CoFe₂O₄ nanoparticle catalyst prepared by hydrothermal method was also investigated.     

Enhancing Sensitivity of Fiber Bragg Grating-Based Temperature Sensors through Teflon Coating

Wireless Personal Communications - As global warming and climate change persistently threaten our planet, especially in developing countries, environmental monitoring becomes more and more...     

Hybrid Zadoff‐Chu and multilateral piecewise exponential companding transform–based PAPR reduction technique in OFDM systems

The orthogonal frequency‐division multiplexing (OFDM) is a multicarrier modulation system that is used to transmit the large volume of data to the receiver. Reducing the peak‐to‐average power ratio (PAPR) in OFDM system is one of the demanding and crucial task in recent days. For this reason, various precoding and companding mechanisms are developed in the traditional works, but it remains with the limitations of increased complexity, reduced performance, and nonlinear distortion. The reduction of PAPR is achieved by minimizing the companding distortion with the enhancement of the bit error rate (BER) performance significantly. Then, in order to avoid clipping in OFDM, a multilateral piecewise exponential companding transform (MPECT) method has been utilized rather than using piecewise exponential companding transform (PEC) where PAPR is getting reduced. The OFDM is very sensitive to synchronizing error. To overcome this sensitivity, employ the Zadoff‐Chu sequence to carrier frequency offsets. Zadoff‐Chu matrix transform (ZCMT) has numerous merits among the other ODFM systems such as the improvement in the performance of the channels that are fading away and provides an ideal periodic autocorrelation and a constant magnitude periodic cross correlation. Both of these techniques provide improvement in the ODFM systems. To get more efficiency, this paper aims to develop a hybrid technique by integrating the ZCMT and MPECT techniques for reducing the PAPR in OFDM systems. Further, convolutional encoding is applied for better BER and PAPR. The simulation results of the proposed ZCMT‐MPECT technique are evaluated and compared with the conventional OFDM and other precoding methods.     

How agile software development methods reduce work exhaustion: Insights on role perceptions and organizational skills

Agile methods are widely used in the software industry as a way to more rapidly develop and deliver new software. They define iterative work processes, advocate self‐organization and openness for change, and prescribe how software developers interact with each other and external stakeholders. Despite their popularity, it is unclear how agile methods influence work exhaustion in software developers and how developer skills play into this effect. On the one hand, agile methods may reduce software developers' work exhaustion by levelling out their workload across the entire duration of a project. On the other hand, agile methods exert a high level of pressure on software developers to continuously deliver working software, create many intensive social interactions, and to frequently adapt to changes. In light of these effects, prior research could not explain why some software developers become less exhausted from using agile methods, whereas others perceive the exact opposite. Based on the job demand‐control model, we develop a theoretical model connecting agile method use to individual developer skills and to two established determinants of employee exhaustion: role conflict and role ambiguity. We tested our research model in a field study among 1894 software developers in 217 project teams that used agile methods. The random coefficient modelling results show that agile method use facilitates the achievement of clear and unambiguous role perceptions and thereby reduces work exhaustion in developers, particularly if developers possess the organizational skills to effectively interact with others in their organization. We highlight implications for theory on the individual‐level effects of software development methods and provide practical insights for software companies.