85000 research outputs found
Sort by
A node moving-based structural topology optimization method in the body-fitted mesh
No full textThe work presents a node-moving algorithm for topology optimization (NMTO) in the arbitrarily shaped design domain. Also, we further enhanced a body-fitted mesh generation algorithm to express smooth boundaries more efficiently. In each optimization iteration, a narrowband offset from the structural profile is established, based on which a signed-distance function is constructed to determine the node-moving direction. At the same time, the magnitude of node velocity is derived from the shape derivative of the objective function - the sum of mean compliance and mean curvature. After the signed-distance function is updated based on the new position of the nodes within the narrowband with the abovementioned velocity, boundaries implicitly represented by its zero-level contour are obtained naturally. Such a forward Euler updating scheme is much more efficient than the well-known upwind algorithm for the body-fitted mesh as it avoids the interpolation of triangular nodes to the rectangular nodes and a small time step. Compared with other methods, benchmark numerical examples demonstrate that the proposed method can produce elegant structures with smoother boundaries and better objective functions for optimization problems seeking maximal stiffness or displacement at a prescribed node. In addition, the proposed approach prevents, to a large extent, useless void parts from being included in the time-consuming finite element analysis
Uncovering Variations in Clinical Notes for NLP Modeling
No full textClinical text contains rich patient information and has attracted much research interest in applying Natural Language Processing (NLP) tools to model it. In this study, we quantified and analyzed the textual characteristics of five common clinical note types using multiple measurements, including lexical-level features, semantic content, and grammaticality. We found there exist significant linguistic variations in different clinical note types, while some types tend to be more similar than others
Programmable high-dimensional Hamiltonian in a photonic waveguide array
No full textWaveguide lattices offer a compact and stable platform for a range of applications, including quantum walks, condensed matter system simulation, and classical and quantum information processing. However, to date, waveguide lattice devices have been static and designed for specific applications. We present a programmable waveguide array in which the Hamiltonian terms can be individually electro-optically tuned to implement various Hamiltonian continuous-time evolutions on a single device. We used a single array with 11 waveguides in lithium niobate, controlled via 22 electrodes, to perform a range of experiments that realized the Su-Schriffer-Heeger model, the Aubrey-Andre model, and Anderson localization, which is equivalent to over 2500 static devices. Our architecture’s micron-scale local electric fields overcome the cross-talk limitations of thermo-optic phase shifters in other platforms such as silicon, silicon-nitride, and silica. Electro-optic control allows for ultra-fast and more precise reconfigurability with lower power consumption, and with quantum input states, our platform can enable the study of multiple condensed matter quantum dynamics with a single device
Analysis of Spectral Estimation Algorithms for Accurate Heart Rate and Respiration Rate Estimation Using an Ultra-Wideband Radar Sensor
No full textNon-contact vital sign monitoring has been an important research topic recently due to the ability to monitor patients for an extended period especially during sleep without requiring uncomfortable attachments. Radar is a popular sensor for vital sign monitoring research. Various algorithms have been proposed for estimating respiration rate and heart rate from the radar data. But many algorithms rely on Fast Fourier Transform (FFT) to convert time domain signal to the frequency domain and estimate vital signs, despite FFT having limitation of frequency resolution being inverse of the time interval of data sample. However, there are other spectral estimation algorithms, which have not been much researched into the suitability of vital sign estimation using radar signals. In this paper, we compared eight different types of spectral estimation algorithms, including FFT, for respiration rate and heart rate estimation of stationary subjects in a controlled environment. The evaluation is based on extensive data consisting of different stationary subject positions. Considering the results, the eligibility of algorithms other than FFT for respiration rate and heart rate estimation is demonstrated. Using this work, researchers can get an overview on which algorithm is suitable for their work without the need to review individual algorithms separately
A toolbox for investigating liquid metal systems
No full textThe exceptional properties of liquid metals at room temperature, such as their fluidity, stretchability, deformability, and potential applications, have rapidly inspired the scientific community. At present, the main challenge is overcoming technical barriers associated with the characterization of liquid metal systems, which have resulted in their molecular structure remaining effectively unknown. This lack of knowledge has significantly hampered the progress of the emerging field of liquid metal chemistry, prohibiting tailored design and relegating researchers to work by trial and error. In recent years, several technological and scientific developments, including improved analytical tools, have emerged that have the potential to tackle the current challenges. In this review, we present a comprehensive appraisal of the various state-of-the-art characterization techniques that can help uncover answers to long-standing questions in the domain of liquid metals and metal-in-metal colloidal systems. We describe selected generic methodologies and several unique approaches that can capture the various changes in the physical and chemical behavior of molten metals in the presence of internal and external stimuli. In combination, the outlined tools will deepen our understanding of liquid metal chemistry and will accelerate research translation to provide solutions in areas such as catalysis, biomedicine, and reconfigurable electronics
Designing a Digital Health Solution: A Platform for Automated Surveillance of Fungal Infection
No full textSurveillance of invasive fungal infection (IFI) requires laborious review of multiple sources of clinical information, while applying complex criteria to effectively identify relevant infections. These processes can be automated using artificial intelligence (AI) methodologies, including applying natural language processing (NLP) to clinical reports. However, developing a practically useful automated IFI surveillance tool requires consideration of the implementation context. We employed the Design Thinking Framework (DTF) to focus on the needs of end users of the tool to ensure sustained user engagement and enable its prospective validation. DTF allowed iterative generation of ideas and refinement of the final digital health solution. We believe this approach is key to increasing the likelihood that the solution will be implemented in clinical practice
Digital interventions for healthy ageing and cognitive health in older adults: a systematic review of mixed method studies and meta-analysis
No full textBackground
Currently, there is no systematic review to investigate the effectiveness of digital interventions for healthy ageing and cognitive health of older adults. This study aimed to conduct a systematic review to evaluate the effectiveness of digital intervention studies for facilitating healthy ageing and cognitive health and further identify the considerations of its application to older adults.
Methods
A systematic review and meta-analysis of literature were conducted across CINAHL, Medline, ProQuest, Cochrane, Scopus, and PubMed databases following the PRISMA guideline. All included studies were appraised using the Mixed Methods Appraisal Tool Checklist by independent reviewers. Meta-analyses were performed using JBI SUMARI software to compare quantitative studies. Thematic analyses were used for qualitative studies and synthesised into the emerging themes.
Results
Thirteen studies were included. Quantitative results showed no statistically significant pooled effect between health knowledge and healthy behaviour (I2 =76, p=0.436, 95% CI [-0.32,0.74]), and between cardiovascular-related health risks and care dependency I2=0, p=0.426, 95% CI [0.90,1.29]). However, a statistically significant cognitive function preservation was found in older adults who had long-term use of laptop/cellphone devices and had engaged in the computer-based physical activity program (I2=0, p<0.001, 95% CI [0.01, 0.21]). Qualitative themes for the considerations of digital application to older adults were digital engagement, communication, independence, human connection, privacy, and cost.
Conclusions
Digital interventions used in older adults to facilitate healthy ageing were not always effective. Health knowledge improvement does not necessarily result in health risk reduction in that knowledge translation is key. Factors influencing knowledge translation (i.e., digital engagement, human coaching etc) were identified to determine the intervention effects. However, using digital devices appeared beneficial to maintain older adults’ cognitive functions in the longer term. Therefore, the review findings suggest that the expanded meaning of a person-centred concept (i.e., from social, environmental, and healthcare system aspects) should be pursued in future practice. Privacy and cost concerns of technologies need ongoing scrutiny from policy bodies. Future research looking into the respective health benefits can provide more understanding of the current digital intervention applied to older adults
Effectiveness of grease interceptors in food service establishments for controlling fat, oil and grease deposition in the sewer system
No full textThe water industry worldwide experiences numerous sewer blockages each year, partially attributed to the accumulation of fat, oil and grease (FOG). Managing this issue involves various strategies, including the requirement for installation of grease interceptors (GIs) installation. However, the claimed efficacy of commercial GIs of eliminating 99 % of FOG has been questioned for many years because FOG deposit formation occurs despite food service establishments (FSEs) using GIs, therefore detailed understanding of FOG wastewater compositions and its removal by GIs is required. This study provides an insight into the key FOG components such as FOG particle size, metals and fatty acid (FA) profile in GI influent and effluent, and within the GI, at three different FSEs. Analysis of FAs identified substantial proportions of extra-long-chain FAs in the effluents, including arachidic (C20:0), behenic (C22:0), mead (C20:3), lignoceric (C24:0), and nervonic (C24:1) acids. In contrast, the household kitchen released palmitic (C16:0), oleic (C18:1) and linoleic (C18:2) acids. It was further observed that scums effectively remove the larger FOG particles, leaving only 10 % below 75.4 μm. Notably, FSEs which employed automatic dishwashers produced up to 80.4 % of particles ≤45 μm, whereas FSEs and household kitchen which used handwash sinks generated only 36.9 % and 26.3 % of particles ≤45 μm, respectively. This study demonstrated that the commercial GIs do not remove FOG entirely but clearly demonstrated that they discharge high concentrations of FOG with extra-long FFAs which were attributed to the occurrence of microbial activity and hydrolysis of triglycerides within the GI, potentially contributing to FOG deposition
Facile synthesis of direct Z-scheme PPy/NH2-UiO-66 heterojunction for enhanced photocatalytic Cr(VI) reduction, industrial electroplating wastewater treatment, and tetracycline degradation
No full textZ-scheme heterojunction photocatalysts generally have excellent redox ability and robust removal efficiency for contaminants in water. Herein, we combined p-type PPy and n-type NH2-UiO-66 by ball milling to prepare a direct Z-scheme PPy/NH2-UiO-66 photocatalyst with ultra-high redox potential. Notably, the optimized efficiency of PPy/NH2-UiO-66 (the mass ratio of PPy to NH2-UiO-66 is 1 wt%, named PPy/NU-1) rapidly reduced Cr(VI) (>95%, 60 min) and TC degradation (>90%, 180 min) at 100 W LED light. Moreover, the PPy/NU-1 has high stability and good anti-interference ability, which can effectively remove Cr(VI) from industrial electroplating wastewater, and the Cr(VI) removal rate is 99%, which meets the industrial wastewater standard and has the potential attraction of actual wastewater treatment. In addition, the techniques of UV-Vis diffuse reflection, electron spin resonance (ESR), photoluminescence (PL), and photoelectrochemical measurement showed that PPy/NH2-UiO-66 composites improved the light capture ability, thereby improving the photocatalytic efficiency. The PPy/NU-1 has a very high redox potential by constructing a Z-scheme heterojunction, enhances the interfacial charge transfer ability, and improves the separation efficiency of photogenerated carriers. Finally, the mechanism of the Z-scheme was systematically by nitroblue tetrazolium (NBT) and p-phthalic acid (TA) transformation, ESR experiments, and density functional theory (DFT) calculations. This work provides a strategy for the preparation of visible photocatalysts with excellent photocatalytic activity and provides new insights for interfacial charge transfer and molecular oxygen activation
Link between shape dependent lifetimes and thermal escape in quantum dots and rings
No full textUnderstanding the optical emission characteristics of semiconductor nanostructures is important when determining their device applicability. Their emission depends on the material and its geometry, but also depends on other processes such as thermal escape from the nanostructure. Although it is widely accepted that scattering involving longitudinal optical phonons is the key process in thermal escape, it remains unclear why some quantum structures thermally emit excitons while others emit uncorrelated electron-hole pairs or single charge carriers. To investigate this phenomenon, we theoretically determine the energy levels and temperature- lifetime relationships of quantum dots and rings. We find that replicating the observed temperature dependence of the exciton lifetime requires both an eigenspectrum and a thermal escape mechanism which are geometry dependent. This suggests that geometry may be a significant factor in determining the dominant thermal escape process in quantum structures