In this work, we have developed a state-based peridynamics theory for nonlinear Reissener-Mindlin shells to model and predict large deformation of shell structures with thick wall. The nonlocal peridynamic theory of solids offers an integral formulation that is an alternative to traditional local continuum mechanics models based on partial differential equations. This formulation is applicable for solving the material failure problems involved in discontinuous displacement fields. The governing equations of the state-based peridynamic shell theory are derived based on the nonlocal balance laws by adopting the kinematic assumption of the Reissner and Mindlin plate and shell theories. In the numerical calculations, the stress points are employed to ensure the numerical stability. Several numerical examples are conducted to validate the nonlocal structure mechanics model and to verify the accuracy as well as the convergence of the proposed shell theory. 相似文献
Sr2+ ions-substituted cobalt ferrite having the composition formula SrxCo1?xFe2O4 (x?=?0.05, 0.10, 0.15, and 0.20) was synthesized with sol–gel method. X-ray diffraction (XRD) patterns proved that the samples had a spinel structure. The Fourier-transform infrared (FTIR) spectra showed that the samples have two characteristic bands about the intrinsic vibrations of spinel ferrite. The morphology and chemical elements were tested by scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS). The elemental state of annealed samples was examined by X-ray photoelectron spectroscopy (XPS). The magnetic data showed the coercivity increased from 954.33 Oe to 1545.54 Oe when the Sr2+ ions content increased. The optical absorption properties of annealed samples were investigated by UV–Vis spectroscopy. Complex impedance spectroscopy showed that grain resistance of Sr0.10Co0.90Fe2O4 sample was 443.9 Ω.
This paper presents our investigation into a 220 GHz multicarrier highspeed communication system based on solid state transceivers.The proposed system has eased the demand of high sampling rate analog-to-digital converter(ADC)by providing several signal carriers in microwave band and converting them to 220 GHz channel.The system consists of a set of 220 GHz solid-state transceiver with 2 signal carriers,two basebands for 4 GSPS ADCs.It has achieved 12.8 Gbps rate real-time signal transmission using 16QAM modulation over a distance of 20 m without any other auxiliary equipment or test instruments.The baseband algorithm overcomes the problem of frequency difference generates by non-coherent structure,which guarantees the feasibility of long-distance transmission application.Most importantly,the proposed system has already carried out multi-channel 8K video parallel transmission through switch equipment,which shows the multicarrier high-speed communication system in submillimeter wave has great application prospects.To the best of the authors’knowledge,this is the first all-solid-state electronics multicarrier communication system in submillimeter and terahertz band. 相似文献
Nowadays, many payment service providers use the discounts and other marketing strategies to promote their products. This also raises the issue of people
who deliberately take advantage of such promotions to reap financial benefits. These people are known as ‘scalper parties’ or ‘econnoisseurs’ which can
constitute an underground industry. In this paper, we show how to use machine learning to assist in identifying abnormal scalper transactions. Moreover,
we introduce the basic methods of Decision Tree and Boosting Tree, and show how these classification methods can be applied in the detection of abnormal
transactions. In addition, we introduce a graph computing method, which implicitly describes the characteristics of people and merchants through node
correlation, in order to mine deep features. Because of the volume of large data, we carried out reasonable block calculation, and succeeded in reducing
a large amount of data to a series of segments, thereby decreasing the computational resources and memory requirements. Compared with other work on
abnormal transaction detection, we pay more attention to creating and using the portraits of merchants or individuals to assist in decision-making. After
data analysis and model building, we find that focusing on only one transaction or one day does not yield a comprehensive number of characteristics,
and many characteristics can be obtained by examining the transactions of a person or a merchant over a period of time. Furthermore, a large number of
characteristics can be obtained from transactions in a period of time. After GBDT (Gradient Boosting Decision Tree) based classification prediction and
analysis, we can conclude that there is a clear distinction between abnormal trading shops and conventional shops, facilitating the clustering of abnormal
merchants. By filtering transaction data from multiple dimensions, multiple sub-graphs can be obtained. After hierarchical clustering, the abnormal trading
group is mined and classified according to its features. Finally, we build a scoring model and apply it to the big data platform of one of China’s largest
payment service providers to help enterprises identify abnormal trading groups and specific marketing strategies. 相似文献
In nature, many biological organisms possess a unique osmoregulation feature that enables them to survive in environments of different salinity, which is called euryhaline characteristics (e.g., salmon that can survive in freshwater and seawater). Drawing inspiration from these salinity-tolerant organisms, here a strategy that integrates two polymer chain segments with different salinity tolerances is reported to produce a euryhaline hydrogel with stable water retention, constant swelling properties, superoleophobicity, and low-adhesion to oil in aqueous environments over a wide range of salinity. The formation of internal dynamic complementary crosslinks is a key structural factor of the euryhaline attributes. The euryhaline hydrogel-coated meshes can be successfully utilized in various oil/aqueous phase separation in a wide range of salinity. Furthermore, by creating a double network with dynamic bonds, superior euryhaline hydrogel with unique salinity-enhanced mechanical strength can be obtained. It is anticipated that the euryhaline hydrogel will have broad application prospects in complex and variable ionic environments. 相似文献
Precise diagnosis of cancer in an early stage and treatments with a reliable response, high selectivity, and negligible side effects is urgently needed. However, current cancer management involves low-resolution metrics and delayed visual confirmation of tumor foci in imaging findings, and the toxicity of chemo- and radiotherapy unavoidably damages normal tissue and disrupts the immune balance of cancer patients. Here, a polypeptide is synthesized that preferentially targets lung cancer cells rather than normal lung epithelial cells and induces calcium precipitation specifically on the plasma membrane of lung cancer cells without additional supplementary calcium. Polypeptide-induced cellular calcification can ideally facilitate medical imaging for identifying early-stage lung cancer and distinguish cancer from benign nodules. Physiological and spontaneous calcification of tumors is induced by polypeptides and sharply prolongs the survival of tumor-bearing mice without evidence of systemic side effects. This tumor cell-selective calcification process provides an attractive, safe, and unprecedented approach for accurately visualizing and treating cancer in patients with early-stage disease in the clinic. It has broad implications in developing simple physiological reactions for diagnosing and treating cancer and provides a new horizon for drug discovery. 相似文献