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Combinational logic circuits based on a power- and area-efficient memristor with low variability
No full textThe saturation of complementary metal–oxide–semiconductor (CMOS) technology in terms of area and power efficiency has given rise to advanced research on nanodevices. Memristors and their switching properties facilitate the implementation of various combinational logics and neural networks by potential replacement of the existing CMOS technology for edge computing devices. This work presents the design, implementation, and performance evaluation of memristor-based combinational logic circuits including adders, subtractors, and decoders via MATLAB Simulink and Cadence Virtuoso. In this work, we propose an optimized design of memristor-based combinational logic circuits and conduct a comparative study with the conventional method. The proposed memristor model is thoroughly validated experimentally for a high-density Y2O3-based memristive crossbar array and shows ultralow values in device-to-device and cycle-to-cycle variability. The power calculated from these circuits is reduced by more than 90% as compared to conventional CMOS technology implemented in Cadence Virtuoso. Moreover, the number of components utilized in the memristor-based logic circuits is significantly reduced in comparison to existing CMOS technology, which makes it more area-efficient and opens new avenues for the design and implementation of complex logic circuitry in few-micrometer scale
Prediction of absorptivity in Multi-Jet Fusion manufactured polypropylene structures through laser flash and corrected porosity method
No full textFor the first time in the literature, this study validates the absorption phenomena in Multi-Jet Fusion (MJF) printed polypropylene (PP) structures through Laser Flash (LFA) and Corrected Porosity (CP) methods. The influence of process parameters such as build height and build orientation was investigated on tensile properties, crystallinity, porosity and thermophysical attributes in MJF printed PP coupons. Results showed that both crystallinity and tensile performance did not significantly vary with either location or build orientation. Interestingly, samples printed in the Z orientation showed a 35% decrease in strain, indicating that Z-oriented MJF coupons were more brittle than the flat samples (XY). Samples printed in Z orientation also possessed higher porosity and relatively lower crystallinity than the XY orientation. However, large deviations within porosity values were an obstacle to determining a suitable build chamber location for manufacturing dense samples. Therefore, a detailed investigation on porosity of printed samples using micro-CT scans and CT image analysis was necessary. Initially, poor contrast was obvious when MJF printed samples were positioned vertically in the micro-CT chamber which was mainly due to high value of horizontal intensity profile (HIP ~ 70%). Contrast in MJF samples improved significantly in the horizontal orientation (HIP ~ 40%). In parallel, the half-time and heat loss were measured in LFA to understand changes in absorption phenomena with height and orientation of the build. A direct correlation was found between LFA half-time and porosity only when the porosity correction method was implemented. Corrected porosity value was found to be inversely proportional to the heat loss of printed PP samples which indicated higher absorption for samples printed in the bottom of build chamber, XY12, whereas lower absorption was observed for less dense Z samples. Finally, heat loss phenomenon was verified using dense reference Pyrocer
High-efficient solar-driven nitrogen fixation by modulating the internal electric-field of MOFs via n-site-enhanced charge density difference in organic ligands
No full textN2 photofixation at ambient conditions plays a key role in environmental stability on earth. Based on the strategy that introducing N sites to change the charge distribution of organic ligands to regulate the internal electric-field, three types of MOFs by doping different organic ligands, namely Zr-PzDC, Zr-PyDC and Zr-BDC were designed and synthesized to fix nitrogen for obtaining enhanced photocatalytic performance. DFT calculations show that the pyrazine ring in Zr-PzDC has a larger charge density difference, which is beneficial to the separation and transmission efficiency of photogenerated electrons and expands the photoresponse range. The surface charge density of the samples was numerically calculated by using the field-only surface integral method. Zr-PzDC demonstrated the best nitrogen photofixation performance of 143.51 μmol·g−1·h−1 under ambient conditions. This study provides a new approach and perspective for the design of MOF photocatalysts for N2 fixation based on designing different organic ligands structure
Co-creating cultural heterotopic spaces in Airbnb
No full textThis article considers the concept of heterotopia in shared tourism accommodation. Based on an auto-ethnographic account and interviews with 27 hosts and guests of Airbnb shared spaces and their Airbnb listings, the article explains how a home with mixed statuses of accommodation and homeyness can provide transitional experiences that link the ordinary and extra-ordinary, order and disorder and conflicting cultural meanings that impact social interaction. We find that Airbnb spaces contain layers of cultural complexity that shape how hosts and guests co-create their exchanges and transition through the space. Applying the concept of heterotopia to a site that disrupts taken-for-granted notions about the ordering of space offers a dynamic view of how the peer-to-peer accommodation experience is co-created. We also develop implications for consumption and service provision within the sharing economy
Metabolic dysfunction-associated steatotic liver disease in older adults is associated with frailty and social disadvantage
No full textBackground & Aims: The burden of metabolic dysfunction-associated steatotic liver disease (MASLD) is growing rapidly, as is the number of older adults globally. However, relatively few studies have been performed evaluating the prevalence and risk factors for MASLD in older adults. As such, we aimed to identify the prevalence of MASLD in older adults, as well as sociodemographic, clinical, functional and biochemical associations. Methods: The study population included older adults without a history of cardiovascular disease, dementia or independence-limiting functional impairment who had participated in the ASPirin in Reducing Events in the Elderly (ASPREE) randomised trial. MASLD was defined using the Fatty Liver Index (FLI). Associations were identified using Poisson regression with robust variance for FLI ≥ 60 vs FLI < 30. Results: 9097 Australian participants aged ≥70 years had complete biochemical and anthropometric data to identify MASLD. The study population had a mean age of 75.1 ± 4.3 years and was 45.0% male. Almost one-third (33.0%) had prevalent MASLD, and the prevalence decreased with increasing age (adjusted RR [aRR] 0.96, 95% CI: 0.96–0.97). MASLD was also negatively associated with social advantage (aRR 0.94, 95% CI: 0.90–0.99) and exercise tolerance and was positively associated with diabetes mellitus (aRR: 1.22, 95% CI: 1.16–1.29), hypertension (aRR: 1.31, 95% CI: 1.22–1.41), male sex (aRR: 1.66, 95% CI: 1.57–1.74), pre-frailty (aRR: 1.99, 95% CI: 1.82–2.12) and frailty (aRR: 2.36, 95% CI: 2.16–2.56). MASLD and nonalcoholic fatty liver disease (NAFLD) results were 100% concordant. Conclusion: This study in a large cohort of relatively healthy community-dwelling older adults shows that MASLD is common, decreases with age and is associated with poorer metabolic health, social disadvantage and frailty
A gradient-evolutionary coupled topology optimization for sheet reinforcement based on the mechanics of Voronoi pattern on dragonfly wings
No full textThe intricate network of veins on dragonfly wings has captured the attention of many researchers due to its fascinating configuration and excellent mechanical properties. In this paper, based on the observation of the layout of the vein domains on the hind wing of dragonfly, the types of domains were characterized from the aspects of area and shape. The numerical analysis revealed that different shaped domains enhance either stiffness or vibration stability of the wing. According to this feature, a multi-objective gradient optimization algorithm based on stiffness, mass transport efficiency and first order frequency was proposed. Associated by the size constraints, the optimal layout of the venation was obtained and subsequently used to generate the Voronoi patterns, whose positions and shapes could be further optimized by an evolutionary algorithm to match the mechanical analysis results. The effectiveness of this multi-cellular configuration was verified by testing the bending and vibration stability of the additive manufactured model. The aerodynamic simulation analysis of this flapping wing structure was also investigated. This study has important implications for understanding the evolutionary mechanisms of venation on biological wings and designing reinforcement for sheets
Buckling analysis of multi-span non-uniform beams with functionally graded graphene-reinforced foams
No full textThis paper conducts the buckling analysis of multi-span functionally graded (FG) beams reinforced by three-dimensional graphene foams (3D-GFs) restrained by elastic supports. The graphene foams are considered as graded variation in the thickness direction according to four different porosity distributions. The width and height of the non-uniform beams vary in the longitudinal direction in accordance with the power-law principle, and the multi-span beams consist of two types of optional beams. The governing equations of buckling behavior are derived based on the Timoshenko beam theory and the principle of virtual displacements, and solved by the discrete singular convolution (DSC) method. The purpose of this paper is to obtain the critical buckling load of FG 3D-GFs reinforced beams under the consideration of variable cross-section and multi-span beams with 2–4 spans. The effect of porosity coefficients, slenderness ratio, and spring constants on the buckling characteristic also are studied. The results suggest that the taper ratio of beams and the configuration of multi-span beams lead to remarkable changes in the critical buckling load of beams
A survey on personalized itinerary recommendation: From optimisation to deep learning
No full textThe tourism industry is a significant contributor to the global economy, responsible for generating nearly 10% of the world's GDP and employing around 9% of the global workforce. A crucial aspect of this industry is personalised itinerary recommendation, where visitors’ preferences and constraints are taken into account to create customised travel plans. This task involves selecting the best points of interests (POIs) for visitors in various cities and then schedule these POIs as an itinerary considering numerous constraints. However, due to the varied ways in which researchers have defined the itinerary recommendations, it can be challenging for new researchers to locate up-to-date literature on the topic. As a result, this paper aims to review existing research in this area and provide a taxonomy of the works based on problem formulations, proposed techniques, constraints, and features used. We divide the study into two directions: user satisfaction and provider satisfaction, where user satisfaction is derived non-personalised and personalised POI/ Itinerary recommendations. We also discuss the data sources, techniques ranging from optimisation approaches to deep learning and evaluation methodologies commonly used in this field. Finally, we highlight the importance of personalised itinerary recommendation and identify areas for future research to address the current challenges
Are fire intensity and burn severity associated? Advancing our understanding of FRP and NBR metrics from Himawari-8/9 and Sentinel-2
No full textBurn severity has been widely studied. Typical approaches use spectral differencing indices from remotely sensed data to extrapolate in-situ severity assessments. Next generation geostationary data offer near-continuous fire behaviour information, which has been used for fire detection and monitoring but remains underutilized for fire impact estimation. Here, we explore the association between remotely sensed fire intensity metrics and spectral differencing severity indices to understand whether and where they describe similar wildfire effects. The commonly used Differenced Normalised Burn Ratio (dNBR) severity index was calculated for Advanced Himawari Imager (AHI − 2 km) and Sentinel-2 (20 m) data and compared to different Fire Radiative Power (FRP) metrics derived from fire hotspot detections from AHI data across Australia. The comparison was implemented through different stratifications based on biogeographical region, land cover, fire type, and percentage of AHI pixel burned (fire fractional cover). The results indicate that FRP and dNBR metrics do not correlate in most scenarios, noting correlations being marginally stronger for hotter fires. However, correlations become significantly stronger when data are grouped using fire type information and fire fractional cover, with correlations peaking (R = 0.75) for large fires that burned 41–60 % of an AHI pixel. In conclusion, remotely sensed fire intensity and severity proxies capture different aspects of wildfire impact, that only correlate with each other after using auxiliary data. Spectral differencing severity metrics have been used extensively during the past decades, however high-frequency fire intensity estimations have the potential to augment the existing information and reveal new ways of characterizing wildfire impact over large areas
A qualitative study of work and early menopause: ‘On-the job’ experiences and career trajectories
No full textObjectives: Early menopause or premature ovarian insufficiency (POI), menopause occurring before age 45 and 40 years respectively, occur at the age when most women are establishing or consolidating their careers. Studies of older postmenopausal women indicate an adverse bidirectional relationship between menopause and work. However, data are lacking regarding the work experiences of women with early menopause or POI. We explored the experiences of women with early menopause or POI in relation to work. Study design: Using maximum variation sampling, 30 women (median age 44 years and 38 years at menopause diagnosis) of diverse backgrounds and menopause causes (16/30 iatrogenic) participated in qualitative interviews to explore experiences of early menopause/POI in the context of their overall lives, work and career. Dual thematic (themes identified across interviews) and thematic narrative (themes identified within individual interviews) analysis was done using NVivo 12 software. Main outcome measures: Themes related to work experiences and influencing factors. Results: Two major themes were identified: ‘on-the-job’ experiences (work performance, bodily presentation and disclosure) and career trajectories (intact and altered). Factors impacting the interaction between work and early menopause/POI included: career (type of work, environment, working conditions), personal (age, socio-economic background, family arrangements, migration history) and menopause experience (spontaneous versus iatrogenic, treatment complexity). Conclusions: Early menopause/POI has multiple impacts on women's work experiences and career trajectories. As with older postmenopausal women, career and personal factors influence younger women's work experience. However, this research highlights differences associated with menopause occurring at an earlier, often unexpected age compared with menopause at the usual age