A study of different types of connections to structural-steel square tubings

Although square tubular element has long been recognized as an ideal structural member, its acceptance was limited by the lack of detailed knowledge on suitable connections related to this geometric shape. It is structurally inefficient to use a strong column poorly connected to a strong beam. So it is necessary to understand, in advance of adoption, the effect and behavior of different types of connections and to develop an efficient structural system. In this study, the ordinary column-to-beam framing with different types of connections has been investigated. The three types of connections are single-plate connection, double-angle connection, and multi-angle connection. Six specimens were prepared, instrumented and tested during this study. The research covers only the important factors affecting the design of a connection, such as the rotation and deflection of the beam end, the moment-rotation and deformation of the connection, and stress distribution and stress concentration on the column wall --Abstract, page i

Low-complexity iterative frequency domain decision feedback equalization

Single-carrier transmission with frequency domain equalization (SC-FDE) offers a viable design alternative to the classic orthogonal frequency division multiplexing technique. However, SC-FDE using a linear equalizer may suffer from serious performance deterioration for transmission over severely frequency-selective fading channels. An effective method of solving this problem is to introduce non-linear decision feedback equalization (DFE) to SC-FDE. In this contribution, a low complexity iterative decision feedback equalizer operating in the frequency domain of single-carrier systems is proposed. Based on the minimum mean square error criterion, a simplified parameter estimation method is introduced to calculate the coefficients of the feed-forward and feedback filters, which significantly reduces the implementation complexity of the equalizer. Simulation results show that the performance of the proposed simplified design is similar to the traditional iterative block DFE under various multipath fading channels but it imposes a much lower complexity than the latter

Is orbital angular momentum always conserved in spontaneous parametric down-conversion?

In the non-linear optical process of type-II spontaneous parametric down-conversion, we present on an experiment showing that the two-photon detection amplitude of the down-converted beams does not generally reproduce the transverse profile of the pump beam that carries non-zero orbital angular momentum. We explain this observation by that orbital angular momentum is not conserved in the type-II non-linear process due to the broken rotational symmetry of the Hamiltonian.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Lett. Revise

Myeloid-Derived Suppressor Cells Impair Alveolar Macrophages through PD-1 Receptor Ligation during Pneumocystis Pneumonia

Myeloid-derived suppressor cells (MDSCs) were recently found to accumulate in the lungs during Pneumocystis pneumonia (PcP). Adoptive transfer of these cells caused lung damage in recipient mice, suggesting that MDSC accumulation is a mechanism of pathogenesis in PcP. In this study, the phagocytic activity of alveolar macrophages (AMs) was found to decrease by 40% when they were incubated with MDSCs from Pneumocystis-infected mice compared to those incubated with Gr-1+ cells from the bone marrow of uninfected mice. The expression of the PU.1 gene in AMs incubated with MDSCs also was decreased. This PU.1 downregulation was due mainly to decreased histone 3 acetylation and increased DNA methylation caused by MDSCs. MDSCs were found to express high levels of PD-L1, and alveolar macrophages (AMs) were found to express high levels of PD-1 during PcP. Furthermore, PD-1 expression in AMs from uninfected mice was increased by 18-fold when they were incubated with MDSCs compared to those incubated with Gr-1+ cells from the bone marrow of uninfected mice. The adverse effects of MDSCs on AMs were diminished when the MDSCs were pretreated with anti-PD-L1 antibody, suggesting that MDSCs disable AMs through PD-1/PD-L1 ligation during PcP

Comparing the contribution of visible-light irradiation, gold nanoparticles, and titania supports in photocatalytic nitroaromatic coupling and aromatic alcohol oxidation

Under visible-light irradiation, gold nanoparticles (Au NPs) supported by titania (TiO₂) nanofibers show excellent activity and high selectivity for both reductive coupling of nitroaromatics to corresponding azobenzene or azoxylbenzene and selective oxidation of aromatic alcohols to corresponding aldehydes. The Au NPs act as active centers mainly due to their localized surface plasmon resonance (LSPR) effect. They can effectively couple the photonic energy and thermal energy to enhance reaction efficiency. Visible-light irradiation has more influence on the reduction than on the oxidation, lowering the activation energy by 24.7 kJ mol⁻¹ and increasing the conversion rate by 88% for the reductive coupling, compared to merely 8.7 kJ mol⁻¹ and 46% for the oxidation. Furthermore, it is found that the conversion of nitroaromatics significantly depends on the particle size and specific surface area of supported Au NPs; and the catalyst on TiO₂(B) support outperforms that on anatase phase with preferable ability to activate oxygen. In contrast, for the selective oxidation, the effect of surface area is less prominent and Au NPs on anatase exhibit higher photo-catalytic activity than other TiO₂ phases. The catalysts can be recovered efficiently because the Au NPs stably attach to TiO₂ supports by forming a well-matched coherent interface observed via high-resolution TEM

HoMM: Higher-order Moment Matching for Unsupervised Domain Adaptation

Minimizing the discrepancy of feature distributions between different domains is one of the most promising directions in unsupervised domain adaptation. From the perspective of distribution matching, most existing discrepancy-based methods are designed to match the second-order or lower statistics, which however, have limited expression of statistical characteristic for non-Gaussian distributions. In this work, we explore the benefits of using higher-order statistics (mainly refer to third-order and fourth-order statistics) for domain matching. We propose a Higher-order Moment Matching (HoMM) method, and further extend the HoMM into reproducing kernel Hilbert spaces (RKHS). In particular, our proposed HoMM can perform arbitrary-order moment tensor matching, we show that the first-order HoMM is equivalent to Maximum Mean Discrepancy (MMD) and the second-order HoMM is equivalent to Correlation Alignment (CORAL). Moreover, the third-order and the fourth-order moment tensor matching are expected to perform comprehensive domain alignment as higher-order statistics can approximate more complex, non-Gaussian distributions. Besides, we also exploit the pseudo-labeled target samples to learn discriminative representations in the target domain, which further improves the transfer performance. Extensive experiments are conducted, showing that our proposed HoMM consistently outperforms the existing moment matching methods by a large margin. Codes are available at \url{https://github.com/chenchao666/HoMM-Master}Comment: Accept by AAAI-2020, codes are available at https://github.com/chenchao666/HoMM-Maste

Analytical model of spread of epidemics in open finite regions

Epidemic dynamics, a kind of biological mechanisms describing microorganism propagation within populations, can inspire a wide range of novel designs of engineering technologies, such as advanced wireless communication and networking, global immunization on complex systems, and so on. There have been many studies on epidemic spread, but most of them focus on closed regions where the population size is fixed. In this paper, we proposed a susceptible-exposed-infected-recovered model with a variable contact rate to depict the dynamic spread processes of epidemics among heterogeneous individuals in open finite regions. We took the varied number of individuals and the dynamic migration rate into account in the model. We validated the effectiveness of our proposed model by simulating epidemics spread in different scenarios. We found that the average infected possibility of individuals, the population size of infectious individuals in the regions, and the infection ability of epidemics have great impact on the outbreak sizes of epidemics. The results demonstrate that the proposed model can well describe epidemics spread in open finite regions