This letter reports an 85 GHz low noise amplifier (LNA) employing derivative superposition based non‐linearity cancellation and a current re‐use topology. The LNA employs a two‐stage stacked ...architecture, each featuring neutralized differential pairs utilizing the same DC current. In derivative superposition, an auxiliary branch consisting of neutralized differential pairs cells is added in the LNA in parallel to stage 1 to ensure non‐linearity cancellation. Layout‐based capacitive neutralization is implemented to improve GMAX, resulting in simplified routing, reduced parasitics, and a more compact layout. The proposed LNA is fabricated in TSMC 28 nm CMOS process and achieves a peak gain of 8.4 dB at 84.2 GHz with a measured 3 dB bandwidth (BW3dB$\text{BW}_{3\text{dB}}$) from 79.4 to 92 GHz. The minimum measured noise figure is 12.8 dB. The LNA draws 34 mA of DC current from a 1.2 V supply. The highly linear LNA with IIP3 +6.5 dBm is tailored for automotive RADAR and 6G receivers.
A high‐performance 85 GHz stacked low noise amplifier is presented, featuring derivative superposition based non‐linearity cancellation. The two‐stage stacked architecture incorporates neutralized differential pairs with an auxiliary branch in parallel to stage 1 for non‐linearity cancellation. Implemented in TSMC 28 nm CMOS, the low noise amplifier achieves 8.4 dB peak gain at 84.2 GHz with 12.6 GHz as 3‐dB bandwidth, drawing 34 mA from a 1.2 V supply. With IIP3 of +6.5 dBm, it is tailored for automotive RADAR and 6G receivers.
Aim
Despite the complexity of population dynamics, most studies concerning current changes in bird populations reduce the trajectory of population change to a linear trend. This may hide more complex ...patterns reflecting responses of bird populations to changing anthropogenic pressures. Here, we address this complexity by means of multivariate analysis and attribute different components of bird population dynamics to different potential drivers.
Location
Czech Republic.
Methods
We used data on population trajectories (1982–2019) of 111 common breeding bird species, decomposed them into independent components by means of the principal component analysis (PCA), and related these components to multiple potential drivers comprising climate, land use change and species' life histories.
Results
The first two ordination axes explained substantial proportion of variability of population dynamics (42.0 and 12.5% of variation in PC1 and PC2 respectively). The first axis captured linear population trend. Species with increasing populations were characterized mostly by long lifespan and warmer climatic niches. The effect of habitat was less pronounced but still significant, with negative trends being typical for farmland birds, while positive trends characterized birds of deciduous forests. The second axis captured the contrast between hump‐shaped and U‐shaped population trajectories and was even more strongly associated with species traits. Species migrating longer distances and species with narrower temperature niches revealed hump‐shaped population trends, so that their populations mostly increased before 2000 and then declined. These patterns are supported by the trends of total abundances of respective ecological groups.
Main Conclusion
Although habitat transformation apparently drives population trajectories in some species groups, climate change and associated species traits represent crucial drivers of complex population dynamics of central European birds. Decomposing population dynamics into separate components brings unique insights into non‐trivial patterns of population change and their drivers, and may potentially indicate changes in the regime of anthropogenic effects on biodiversity.
The ePix10ka2M (ePix10k) is a new large area detector specifically developed for X‐ray free‐electron laser (XFEL) applications. The hybrid pixel detector was developed at SLAC to provide a hard X‐ray ...area detector with a high dynamic range, running at the 120 Hz repetition rate of the Linac Coherent Light Source (LCLS). The ePix10k consists of 16 modules, each with 352 × 384 pixels of 100 µm × 100 µm distributed on four ASICs, resulting in a 2.16 megapixel detector, with a 16.5 cm × 16.5 cm active area and ∼80% coverage. The high dynamic range is achieved with three distinct gain settings (low, medium, high) as well as two auto‐ranging modes (high‐to‐low and medium‐to‐low). Here the three fixed gain modes are evaluated. The resulting dynamic range (from single photon counting to 10000 photons pixel−1 pulse−1 at 8 keV) makes it suitable for a large number of different XFEL experiments. The ePix10k replaces the large CSPAD in operation since 2011. The dimensions of the two detectors are similar, making the upgrade from CSPAD to ePix10k straightforward for most setups, with the ePix10k improving on experimental performance. The SLAC‐developed ePix cameras all utilize a similar platform, are tailored to target different experimental conditions and are designed to provide an upgrade path for future high‐repetition‐rate XFELs. Here the first measurements on this new ePix10k detector are presented and the performance under typical XFEL conditions evaluated during an LCLS X‐ray diffuse scattering experiment measuring the 9.5 keV X‐ray photons scattered from a thin liquid jet.
The ePix10ka2M is a new large area detector specifically developed for X‐ray free‐electron laser applications. Here the detector parameters and performance are presented, as well as the detector nonlinearity as characterized by diffuse scattering measurements at the Linac Coherent Light Source.
•Prediction of local buckling resistance of aluminium angles by means of a theoretical procedure.•Definition of an analytical formulation to evaluate the interaction effects of the plate constituting ...the section.•Application of the advanced effective thickness method proposed in Annex L of prEN 1999–1-1.•Comparison between the experimental results with those obtained by the new methodologies: the Deformation Theory of Plasticity (DTP) and the Effective Thickness Method (ETM).•Analysis and comparison of the current design formulas in the evaluation of the ultimate compressive resistance of aluminium angles.
A theoretical approach for the evaluation of the ultimate resistance of aluminium angles subjected to local buckling under uniform compression is presented and compared with simplified approaches used for codification purposes. In particular, a theoretical procedure has been developed by considering the interaction of the outstand elements constituting the cross-section and the mechanical non-linearity of the material. To evaluate the accuracy of the theoretical approach, the results have been compared with experimental tests provided in the scientific literature. Then, a new mathematical formulation has been also derived to estimate the interaction effects of the section plates and it has been used for the extension of the Effective Thickness Method (ETM) according to the new version of Eurocode 9. Finally, the accuracy of simplified approaches as well is investigated by comparing the obtained values with the experimental results derived from the stub column tests reported in the scientific literature.
•Detailed exploration of non-linear association between COVID-19 and area deprivation.•Association strength and sign varies between places depending on deprivation degree.•Distributional pattern of ...association evolved along waves.•Important to control for contextual confounding factors.•Changes in association consistent with variations along waves in nonpharmaceutical interventions and vaccination.
This ecological study assesses the association between the incidence rate of COVID-19 confirmed cases and socioeconomic deprivation in the Catalan small areas for the first six waves of the pandemic. The association is estimated using Poisson regressions and, in contrast to previous studies, considering that the relationship is not linear but rather depends on the degree of deprivation. The results show that the association between deprivation and incidence varied between waves, not only in intensity but also in its sign. Although it was insignificant in the first, third and fourth waves, the association was positive and significant in the second, becoming significantly negative in the fifth and sixth waves. Interestingly, the evidence suggests that the link between both magnitudes was not homogeneous throughout the distribution of deprivation, the pattern also varying between waves. The results are discussed in view of the role of non-pharmacological interventions and vaccination, as well as potential biases (for example that associated with differences between population groups in the propensity to be tested in each wave).
This paper reports a method to construct the complete constitutive model of carbon fiber‐reinforced plastic (CFRP) by distinguishing the strain rate state and modifying the material stiffness. In ...quasistatic (low strain rate) compression, the initial nonlinear effect caused by the material defects was described by introducing an nonlinear increasing factor. In dynamic (high strain rate) impact, the nonlinear strengthening effect was described by introducing the dynamic amplification factors of stress and strain based on the reference state. Considering the instantaneous temperature rise obtained from the impact work–temperature generation equation and the influence of temperature on modulus and strength, the coupled thermomechanical constitutive models combining the strain rate effect and the temperature effect were established. The user‐defined material subroutines (VUMAT) were developed, and then these constitutive models were verified by finite element analysis (FEA). Finally, the developed material subroutine was applied to predict the impact penetration of CFRP laminates, and the results show that the opening holes, damage and energy dissipation are in good agreement with the reference experiment. This work comprehensively analyzed the construction method of CFRP constitutive models, which would provide a guidance for the coupled thermomechanical behavior under dynamic impact.
Highlights
An anisotropic continuum mechanical constitutive behavior considering strain rate effect and damage evolution behavior was established.
A macroscopic anisotropic constitutive model including the coupled impact temperature generation‐mechanical behavior was established.
Combined with the incremental finite element method, the three‐dimensional user‐defined material subroutines (VUMAT) were developed and verified.
The thermomechanical impact penetration behaviors of CFRP laminates was predicted, and the stress field, temperature field and failure characteristics were visualized.
A construction method of CFRP constitutive models under low strain rate compression and high strain rate impact.
Cadmium Sulfide (CdS) nanoparticles play an important role in non-linear optoelectronic devices. CdS/Polystyrene(PS) nanocomposite has been prepared by chemical ex-situ route and characterized by ...X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet–visible (UV–vis) and Photoluminescence (PL) spectroscopy. XRD spectra of CdS/PS nanocomposite reveals the cubic phase of CdS nanoparticles with average crystallite size ~2.54nm. The vibrational band corresponding to Cd–S bond has been observed at 406.57cm−1 in FTIR spectra of CdS/PS nanocomposite along the typical styrene bonds. Quantum confinement effect in the CdS/PS nanocomposite has been confirmed from the UV–vis spectra. In PL emission spectra, in addition to band to band transition emission, the green and yellow bands have been observed due to the interstitial sulfur and cadmium defect states respectively. Z-scan technique has been utilized to study the non-linear optical properties of the CdS/PS nanocomposite. The value of non-linear absorption coefficient (β) and non-linear refractive index (n2) has been calculated. The large value of third order non-linear susceptibility is due to the quantum confinement effect plus the thermal lensing effect produced across the sample.
•CdS/PS nanocomposite prepared by chemical ex-situ technique.•Structural characterization done by XRD and FTIR spectroscopy.•Optical characterization done by UV–vis and Photoluminescence spectroscopy.•Non-linear optical study by single beam Z-scan technique.•Extraction of non-linear parameters such as β, n2 and χ.
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