Test and Finite Element Analysis on Distortional Buckling of Cold-formed Thin-walled Steel Lipped Channel Columns

High-strength cold-formed thin-walled steel sections have been widely used in the recent several years. However, distortional buckli ng or interaction between it and local buckling can occur for high strength cold-formed thin- walled steel members. This paper desc ribes a series of compression tests performed on lipped channel section columns with V-shape intermediate stiffener in the web and flanges fabricated from cold-formed high strength steel of thickness 0.48 and 0.6mm with nominal yield stress 550MPa. The lipped channel sections were tested to failure with both ends of the columns fixed. The test results of 16 specimens show that the local buckling usually appears before distortional buckling of the specimens and it makes the distortional buckling occur in advance. This interaction of local and distortional buckling may have the effect of reducing the stiffness and bearing capacity of the columns. The comparison on ultimate strength and buckling mode between test results and results of finite element analysis considering geometric and material nonlinear show that finite element method (FEM) can simulate the distortional buckling of cold-formed steel channel columns effectively. The calculative results using Direct Strength Method (DSM) of the North American Specification show that this design method couldn’t consider the reverse effect of interaction between local and distortional buckling on ultimate strength. Direct Strength Method (DSM) considering interaction between local and distortional buckling should be developed

4,4′-[Piperazine-1,4-diylbis(propyl­ene­nitrilo­methyl­idyne)]diphenol

In the title mol­ecule, C24H32N4O2, the piperazine ring adopts a chair conformation and the dihedral angle between the two benzene rings is 35.4 (1)°. In the crystal structure, inter­molecular O—H⋯N hydrogen bonds link mol­ecules into chains along [001]

Improved fuzzy logic method to distinguish between meteorological and non-meteorological echoes using C-band polarimetric radar data

To obtain better performance of meteorological applications, it is necessary to distinguish radar echoes from meteorological and non-meteorological targets. After a comprehensive analysis of the computational efficiency and radar system characteristics, we propose a fuzzy logic method that is similar to the MetSignal algorithm; the performance of this method is improved significantly in weak-signal regions where polarimetric variables are severely affected by noise. In addition, post-processing is adjusted to prevent anomalous propagation at a far range from being misclassified as meteorological echo. Moreover, an additional fuzzy logic echo classifier is incorporated into post-processing to suppress misclassification in the melting layer. An independent test set is selected to evaluate algorithm performance, and the statistical results show an improvement in the algorithm performance, especially with respect to the classification of meteorological echoes in weak-signal regions

Exploring human resource management in the top five global hospitals: a comparative study

BackgroundThe pivotal role of Human Resource Management (HRM) in hospital administration has been acknowledged in research, yet the examination of HRM practices in the world’s premier hospitals has been scant.ObjectiveThis study explored how the world’s leading hospitals attain operational efficiency by optimizing human resource allocation and melding development strategies into their HRM frameworks. A comparative analysis of the HRM frameworks in the top five global hospitals was undertaken to offer a reference model for other hospitals.MethodsThis research offers a comparative exploration of the HRM frameworks utilized by the top five hospitals globally, underscoring both shared and distinct elements. Using a multi-case study methodology, the research scrutinized each hospital’s HRM framework across six modules, drawing literature from publicly accessible sources, including websites, annual reports, and pertinent English-language scholarly literature from platforms such as Google Scholar, PubMed, Medline, and Web of Science.ResultsThe analyzed hospitals exhibited inconsistent HRM frameworks, yet all manifested potent organizational cultural attributes and maintained robust employee training and welfare policies. The design of the HR systems was strategically aligned with the hospitals’ objectives, and the study established that maintaining a sustainable talent system is pivotal to achieving hospital excellence.ConclusionThe HRM frameworks of the five analyzed hospitals align with their developmental strategies and exhibit unique organizational cultural attributes. All five hospitals heavily prioritize aligning employee development with overall hospital growth and place a spotlight on fostering a healthy working environment and nurturing employees’ sense of achievement. While compensation is a notable performance influencer, it is not rigorously tied to workload in these hospitals, with employees receiving mid-to-upper industry-range compensation. Performance assessment criteria focus on job quality and aligning employee actions with organizational values. Comprehensive welfare and protection are afforded to employees across all five hospitals

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

Influence of thermocouple angles and wire distance on temperature measurement

When a thermocouple is used to measure gas temperature, the measured temperature, i.e., the thermocouple bead temperature, is not equal to the gas temperature. The bead temperature results from the bead energy balance. The positioning angles such as the pitch angle and the roll angle and the wire distance of the thermocouple will influence the convection heat transfer of the thermocouple, causing the bead temperature variation. Two S type thermocouples are used to measure the temperature of the H2/air Hencken flame with the equivalence ratio 0.7. The maximum measurement temperature changes are 52 K and 79 K for the pitch angle variation and the roll angle variation, respectively. CFD simulations are carried out to simulate the experimental phenomena. The differences between the simulated and measured bead temperatures are less than 20.4 K. With 90° roll angle, the bead temperature increases first then decreases with the pitch angle. With 90° pitch angle, the bead temperature increases first then decreases with the roll angle. With 0° pitch angle, the bead temperature increases monotonically with the wire distance. The background physical mechanisms of the phenomena are analyzed with the detailed CFD results

Thermocouple Effective Length under Sinusoidal Gas Temperature Condition

When a thermocouple is used to measure gas temperature, the measured temperature is the thermocouple bead temperature, which is not equal to the gas temperature. The bead temperature results from its energy balance. Through the wire convection and conduction, the temperature of the bead is related to the gas temperature within a certain geometric range around it, and this range is quantified by the effective length. Under the sinusoidal incoming gas temperature condition, the analytical expression for the effective length is deduced, and its accuracy is validated by the one-dimensional numerical solution. The differences between the analytical and numerical effective lengths are less than 10.5% for the test cases. Similar to that under the uniform incoming gas temperature condition, the effective length under the sinusoidal gas temperature condition increases with the thermal conductivity and the diameter of the wire and decreases with the heat transfer coefficient of the wire. The influence of the amplitude, wavelength and phase of the gas temperature on the effective length are very weak, meaning that the theoretical expression under the uniform gas temperature can calculate the effective length under the non-uniform gas temperature with good accuracy

Thermocouple Effective Length under Sinusoidal Gas Temperature Condition

When a thermocouple is used to measure gas temperature, the measured temperature is the thermocouple bead temperature, which is not equal to the gas temperature. The bead temperature results from its energy balance. Through the wire convection and conduction, the temperature of the bead is related to the gas temperature within a certain geometric range around it, and this range is quantified by the effective length. Under the sinusoidal incoming gas temperature condition, the analytical expression for the effective length is deduced, and its accuracy is validated by the one-dimensional numerical solution. The differences between the analytical and numerical effective lengths are less than 10.5% for the test cases. Similar to that under the uniform incoming gas temperature condition, the effective length under the sinusoidal gas temperature condition increases with the thermal conductivity and the diameter of the wire and decreases with the heat transfer coefficient of the wire. The influence of the amplitude, wavelength and phase of the gas temperature on the effective length are very weak, meaning that the theoretical expression under the uniform gas temperature can calculate the effective length under the non-uniform gas temperature with good accuracy

Particulate Characteristics during a Haze Episode Based on Two Ceilometers with Different Wavelengths

To investigate the particulate characteristics of a haze episode, data from two ceilometers with wavelengths of 532 nm and 910 nm, respectively, were studied intensively. By combining the data from the ceilometers with data from a sounding balloon, an automatic meteorological station, and a Grimm 180 PM instrument, analyses of the haze process of a short haze event were performed. The results showed that the relatively calm weather conditions were favorable to the occurrence of the haze and that higher relative humidity had a great influence on visibility. The extinction profiles from the ceilometers reflected the existence of an inverted structure of the temperature profiles and demonstrated the extinction differences at two different wavelengths. Because extinction has a positive correlation with relative humidity, the effect of hygroscopic growth was analyzed at the two different wavelengths. As hygroscopic growth of the particles proceeded, the longer wavelength became more sensitive to the large particles, and vice versa. The hygroscopic growth factor and the Angstrom exponent showed a negative correlation, and the correlation coefficients at 532 nm and 910 nm were 0.54 and 0.86, respectively. The accumulation mode particles were more stable through time than the coarse mode particles, and the variation of the coarse mode particles coincided well with the variation of the Angstrom exponent from the two ceilometers

Development of a Sinusoidal Corrugated Dual-Axial Flexure Mechanism for Planar Nanopositioning

Taking advantage of the concurrent stretching and bending property of corrugated flexure hinges, a sinusoidal corrugated flexure linkage was proposed and applied for the construction of a corrugated dual-axial mechanism with structural symmetry and decoupled planar motion guidance. Castigliano’s second theorem was employed to derive the complete compliance for a basic sinusoidal corrugated flexure unit, and matrix-based compliance modeling was then applied to find the stiffness of the sinusoidal corrugated flexure linkage and the corrugated dual-axial mechanism. Using established analytical models, the influence of structural parameters on the stiffness of both the corrugated flexure linkage and the dual-axial mechanism were investigated, with further verification by finite element analysis, with errors less than 20% compared to the analytical results for all cases. In addition, the stiffness of the corrugated flexure mechanism was practically tested, and its deviation between practical and analytical was around 7.4%. Further, the feasibility of the mechanism was demonstrated by successfully applying it for a magnetic planar nanopositioning stage, for which both open-loop and closed-loop performances were systematically examined. The stage has a stroke around 130 μm for the two axes and a maximum cross-talk less than 2.5%, and the natural frequency is around 590 Hz