Channel sensing for holographic MIMO surfaces based on interference principle

The Holographic Multiple-Input and Multiple-Output (HMIMO) provides a new paradigm for building a more cost-effective wireless communication architecture. In this paper, we derive the principles of holographic interference theory for electromagnetic wave reception and transmission, whereby the optical holography is extended to communication holography and a channel sensing architecture for holographic MIMO surfaces is established. Unlike the traditional pilot-based MIMO channel estimation approaches, the proposed architecture circumvents the complicated processes like filtering, analog to digital conversion (ADC), down conversion. Instead, it relies on interfering the object waves with a pre-designed reference wave, and therefore reduces the hardware complexity and requires less time-frequency resources for channel estimation. To address the self-interference problem in the holographic recording process, we propose a phase shifting-based interference suppression (PSIS) method according to the structural characteristics of communication hologram and interference composition. We then propose a Prony-based multi-user channel segmentation (PMCS) algorithm to acquire the channel state information (CSI). Our theoretical analysis shows that the estimation error of the PMCS algorithm converges to zero when the number of HMIMO surface antennas is large enough. Simulation results show that under the holographic architecture, our proposed algorithm can accurately estimate the CSI in multi-user scenarios

A stabilized multiple time step method for coupled Stokes-Darcy flows and transport model

A stabilized finite element algorithm with different time steps on different physical variables for the coupled Stokes-Darcy flows system with the solution transport is studied. The viscosity in the model is assumed to depend on the concentration. The nonconforming piecewise linear Crouzeix-Raviart element and piecewise constant are used to approximate velocity and pressure in the coupled Stokes-Darcy flows system, and conforming piecewise linear finite element is used to approximate concentration in the transport system. The time derivatives are discretized with different step sizes for the partial differential equations in these two systems. The existence and uniqueness of the approximate solution are unconditionally satisfied. A priori error estimates are established, which also provides a guidance on the ratio of time step sizes with respect to the ratio of the physical parameters. Numerical examples are presented to verify the theoretical results

A Design Method to Minimize Detuning for Double Sided LCC Compensated IPT System Improving Efficiency Versus Air Gap Variation

Inductive power transfer (IPT) technology has garnered considerable attention due to its widespread range of applications. The variation in the air gap can result in variations in the loosely coupled transformer (LCT) parameters, including self-inductance and mutual inductance, due to positional deviations with the ferrite cores on both sides. These variable LCT parameters can damage the resonant tank, ultimately resulting in reduced efficiency. To address this problem, a double-sided LCC-compensated IPT system with a compact decoupled coil is proposed in this paper to improve the system's efficiency with respect to the air gap variation. The key idea is to neutralize the variation in LCT parameters through the use of the self-inductance variation of the decoupled coil so that the detuning degree of the system can be suppressed. Subsequently, the analysis and parametric design process of the system are elaborated. Finally, a 1 kW experimental setup is built to verify the feasibility of the proposed method. Experimental results show that the efficiency of the system proposed in this work varies from 92.63% to 74.81%, as the air gap increases from 30mm to 90mm, wherein the primary and secondary self-inductance and mutual inductance increased by 19.3% and 135.3%, respectively. Compared with the traditional method, the maximum efficiency improvement is up to 8.16%

Genetic and molecular analysis of the anthocyanin pigmentation pathway in Epimedium

IntroductionFlower color is an ideal trait for studying the molecular basis for phenotypic variations in natural populations of species. Epimedium (Berberidaceae) species exhibit a wide range of flower colors resulting from the varied accumulation of anthocyanins and other pigments in their spur-like petals and petaloid sepals.MethodsIn this work, the anthocyanidins of eight different Epimedium species with different floral pigmentation phenotypes were analyzed using HPLC. Twelve genes involved in anthocyanin biosynthesis were cloned and sequenced, and their expression was quantified.ResultsThe expression levels of the catalytic enzyme genes DFR and ANS were significantly decreased in four species showing loss of floral pigmentation. Complementation of EsF3’H and EsDFR in corresponding Arabidopsis mutants together with overexpression of EsF3’5’H in wild type Arabidopsis analysis revealed that these genes were functional at the protein level, based on the accumulation of anthocyanin pigments.DiscussionThese results strongly suggest that transcriptional regulatory changes determine the loss of anthocyanins to be convergent in the floral tissue of Epimedium species

Model-Free Adaptive Iterative Learning Bipartite Containment Control for Multi-Agent Systems

This paper studies the bipartite containment tracking problem for a class of nonlinear multi-agent systems (MASs), where the interactions among agents can be both cooperative or antagonistic. Firstly, by the dynamic linearization method, we propose a novel model-free adaptive iterative learning control (MFAILC) to solve the bipartite containment problem of MASs. The designed controller only relies on the input and output data of the agent without requiring the model information of MASs. Secondly, we give the convergence condition that the containment error asymptotically converges to zero. The result shows that the output states of all followers will converge to the convex hull formed by the output states of leaders and the symmetric output states of leaders. Finally, the simulation verifies the effectiveness of the proposed method

On the research of cultural relic restoration under reverse design

At present, artificial restoration of cultural relics has been unable to solve the difficulties in restoration and protection of cultural relics, as well as low restoration rate a series of problems. In order to solve the above problems, this article conducts in-depth research on the emerging computer technology that can be used for cultural relic restoration, and proposes a computer-aided cultural relic restoration and reconstruction process based on the reverse design method, and explains the application of 3D printing technology to the restoration of ceramic cultural relics. In this paper, the unearthed cultural relics are protected to the maximum extent research, which provides a reference for improving the scientific nature and durability of cultural relics protection and inheritance

Ingenious Sandwich-like Adhesive Films and Controllable Introduction of Fluorine-Containing Groups toward Strong Adhesive Strength and Low Dielectric Characteristics

In the manufacturing field of high-frequency print circuit boards (HFPCBs), traditional adhesive films (such as epoxy resin and polyimide adhesive films) have attracted enormous attention because of their superior adhesive property. However, their molecular chains intrinsically contained numerous polar groups (carboxyl, carbonyl, and amino), which markedly increased the dielectric constant (Dk) and dielectric loss (Df) of the adhesive film, causing miserable deterioration of the fidelity and transmission rate of signals. In this work, a novel sandwich-like adhesive film was felicitously designed and fabricated by double-sided coating. The core layer as a supporting structure was a polytetrafluoroethylene film with a low dielectric constant and low dielectric loss, and the surface layer as a principal part of the adhesive function was polybutadiene with high vinyl content. Moreover, to further improve the interfacial adhesive strength between the adhesive film and copper foil, the fluorine-containing groups were controllably introduced onto the surface of the sandwich-like adhesive film via environment-friendly plasma treatment. Based on low polarizability and only superficial distribution of the fluorine-containing groups, the interfacial adhesive strength of the film greatly improved from 0.41 to 1.09 N/mm. Unexpectedly, the high-frequency dielectric properties slightly changed (without treatment Dk = 2.42 and Df = 0.0036 at 10 GHz, treatment Dk = 2.46 and Df = 0.0039 at 10 GHz). This work provided the key adhesive materials for the next generation of high-throughput data transmission equipment, remote sensing controllers, and unmanned aerial vehicles in high-frequency ranges

Research on the Fatigue Properties of Rejuvenated Asphalt Prepared by Waste Cooking Oil Pre-Desulfurized Crumb Tire Rubber

Fatigue cracking has hitherto been a crucial constraint on the development of reclaimed asphalt pavements attributed to the performance of rejuvenated asphalt binder. Therefore, it is extremely significant to evaluate the fatigue performance of rejuvenated asphalt precisely and objectively and to improve the fatigue life of rejuvenated asphalt binders. With preceding research in our group, this paper investigated the fatigue properties of waste rubber/oil (WRO) rejuvenated asphalt and universal rejuvenated asphalt by dynamic shear rheometer test (DSR). The applicability of common fatigue life evaluation indexes and the response to internal and external influences on the fatigue performance of rejuvenated asphalt were analyzed. It is demonstrated that Np20 corresponding to the mutagenesis of phase angle is physically significant and independent of the parameters including rejuvenator type, loading mode and loading level, which was recommended as the evaluation index for fatigue life of rejuvenated asphalt in this paper. The fatigue performance of both WRO and universal rejuvenated asphalt is found to decrease with loading frequency and loading level, but the fatigue life of WRO rejuvenated asphalt is comparatively superior to the latter, particularly at high loading frequencies and levels. Influenced by waste tire crumb rubber (WTCR), increasing the proportion of WTCR can improve the fatigue life of rejuvenated asphalt. When compared to other rejuvenated asphalt, RWRO@55 rejuvenated asphalt shows better fatigue performance and its fatigue life rebounds at high loading frequency. Consequently, the recommended mastic–oil ratio is 5:5. However, when the rheological recoverability compensation is considered, the fatigue lifetime evaluation of rejuvenated asphalt will be changed significantly, and therefore the fatigue performance evaluation of rejuvenated asphalt should consider the influence of rheological recoverability to develop a comprehensive evaluation system