Incorporating Lasso Regression to Physics-Informed Neural Network for Inverse PDE Problem

Partial Differential Equation(PDE)is among the most fundamental tools employed to model dynamic systems.Existing PDE modeling methods are typically derived from established knowledge and known phenomena,which are time-consuming and labor-intensive.Recently,discovering governing PDEs from collected actual data via Physics Informed Neural Networks(PINNs)provides a more efficient way to analyze fresh dynamic systems and establish PEDmodels.This study proposes Sequentially Threshold Least Squares-Lasso(STLasso),a module constructed by incorporating Lasso regression into the Sequentially Threshold Least Squares(STLS)algorithm,which can complete sparse regression of PDE coefficients with the constraints of l0 norm.It further introduces PINN-STLasso,a physics informed neural network combined with Lasso sparse regression,able to find underlying PDEs from data with reduced data requirements and better interpretability.In addition,this research conducts experiments on canonical inverse PDE problems and compares the results to several recent methods.The results demonstrated that the proposed PINN-STLasso outperforms other methods,achieving lower error rates even with less data.

Hierarchical Encapsulation and Rich sp^(2)N Assist Sb_(2)Se_(3)-Based Conversion-Alloying Anode for Long-Life Sodium-and Potassium-Ion Storage

Sodium-and potassium-ion batteries have exhibited great application potential in grid-scale energy storage due to the abundant natural resources of Na and K.Conversion-alloying anodes with high theoretical capacity and low-operating voltage are ideal option for SIBs and PIBs but suffer the tremendous volume variations.Herein,a hierarchically structural design and sp^(2)N-doping assist a conversion-alloying material,Sb_(2)Se_(3),to achieve superior life span more than 1000 cycles.It is confirmed that the Sb_(2)Se_(3)evolves into nano grains that absorb on the sp^(2)N sites and in situ form chemical bonding of C-N-Sb after initial discharge.Simulation results indicate that sp^(2)N has more robust interaction with Sb and stronger adsorption capacities to Na^(+)and K^(+)than that of sp3 N,which contributes to the durable cycling ability and high electrochemical activity,respectively.The ex situ transmission electron microscopy and X-ray photoelectron spectroscopy results suggest that the Sb_(2)Se_(3)electrode experiences conversion-alloying dual mechanisms based on 12-electron transfer per formula unit.

A Networking Solution on Uplink Channel of CoFrequency and Co-Time System

Co-frequency and co-time full duplex(CCFD) is an attractive technology for the future wireless communication because of its high spectral efficiency.However,applications of CCFD to mobile network can suffer from strong base station to base station(B2B)interference.In this paper,the authors proposed a design that uses centralized base station(BS)transmit antenna and distributed BS receive antennas,each of which consists of an antennary to perform beamforming that can nullify the B2 B interference.In addition,we proposed a combination algorithm that uses the zero forcing method to cascade the recursive least square(RLS) method for reducing the necessary number of the bits taken to the digital processor.This enables the faster convergence and,thus,allows the transmission of more information bits,compared to the conventional method,for mobile communication.The simulation results confirm this approach for practical application.

Magnetic-conductive bi-gradient structure design of CP/PGFF/Fe 3 O 4 composites for highly absorb e d EMI shielding and balanced mechanical strength

Developing excellent absorption-dominant electromagnetic interference(EMI)shielding composites is an urgent demand for the rapid development of 5 G technology and electronic equipment.Herein,a simple strategy is employed to fabricate carbon nanotubes-polypropylene fibers(CP)/polypropylene-glass fibers felt(PGFF)/Fe 3 O 4 composites with superior EMI shielding effectiveness and low reflection due to the magnetic-conductive bi-gradient structure which is naturally formed by deposition during the vacuum-assisted filtration process.The difference in dimensionality between one-dimensional CNT with outstand-ing electrical conductivity and zero-dimensional magnetic Fe 3 O 4 nanoparticles is the theoretical basis for the successful construction of the magnetic-conductive bi-gradient structure in a gap-rich PGFF matrix that endows the composites with“absorb-reflect-reabsorb”EMI shieldingmechanism.Whentheelectro-magnetic waves are incident from the magnetic layer,the EMI shielding effectiveness(SE)reaches 48.9 dB as the weight percentage of the conductive layer increases,more importantly,the reflection coefficients are reduced by more than 0.32 compared with that of another incident pattern.What’s more,the re-sultant composites exhibit an outstanding signal shielding function in the application.This work paves a convenient pathway for designing a magnetic-conductive bi-gradient structure and efficient absorbing EMI shielding composites applied in the next-generated electronic information and communication field.

Physics-Informed Deep Neural Network for Bearing Prognosis with Multisensory Signals

Prognosis of bearing is critical to improve the safety,reliability,and availability of machinery systems,which provides the health condition assessment and determines how long the machine would work before failure occurs by predicting the remaining useful life(RUL).In order to overcome the drawback of pure data-driven methods and predict RUL accurately,a novel physics-informed deep neural network,named degradation consistency recurrent neural network,is proposed for RUL prediction by integrating the natural degradation knowledge of mechanical components.The degradation is monotonic over the whole life of bearings,which is characterized by temperature signals.To incorporate the knowledge of monotonic degradation,a positive increment recurrence relationship is introduced to keep the monotonicity.Thus,the proposed model is relatively well understood and capable to keep the learning process consistent with physical degradation.The effectiveness and merit of the RUL prediction using the proposed method are demonstrated through vibration signals collected from a set of run-to-failure tests.

Negative compressibility property in hinging open-cell Kelvin structure

A new three-dimensional(3D)cellular model based on hinging open-cell Kelvin structure is proposed for its negative compressibility property.It is shown that this model has adjustable compressibility and does exhibit negative compressibility for some certain conformations.And further study shows that the images of compressibility are symmetrical about the certain lines,which indicates that the mechanical properties of the model in the three axial directions are interchangeable and the model itself has a certain geometric symmetry.A comparison of the Kelvin model with its anisotropic form with the dodecahedron model shows that the Kelvin model has stronger negative compressibility property in all three directions.Therefore,a new and potential method to improve negative compressibility property can be derived by selecting the system type with lower symmetry and increasing the number of geometric parameters.

SnTe nanoparticles physicochemically encapsulated by double carbon as conversion-alloying anode materials for superior potassium-ion batteries

Telluride tin(SnTe)is a promising conversion-alloying anode for potassium-ion batteries(PIBs)due to its high theoretical specific capacity induced by multi-electron transport reaction and low operating voltage,whereas huge volume expansion and poor kinetics behavior become key scientific bottleneck limiting the battery performances.Herein,SnTe nanoparticles physicochemically wrapped by graphene and nitrogen-doped carbon(SnTe@rGO@NC)are proposed as anode materials for PIBs.The pre-electrostatic interaction urges the formation of Sn-C and Te-C chemical bonds between SnTe and double carbon to strengthen the interfacial stability and electron transfer,and the conductive architecture with hierarchical encapsulation effect is beneficial to maintaining the electrode integrity and electrochemical dynamics.It is demon-strated from first principles calculations and experimental results that SnTe@rGO@NC contributes fast electron transmission,strong K-ion adsorption,and superior K-ion diffusion capability.Ex-situ characteri-zations uncover that SnTe undergoes conversion-alloying dual-mechanism with the products of K_(2)Te and K_(4)Sn_(23)replied on Sn redox site(23SnTe+50K^(+)+50e^(-)↔K_(4)Sn_(23)+23K_(2)Te).Thus,the SnTe@rGO@NC electrode delivers a high initial charge specific capacity of 243.9 mAh g^(-1)at 50 mA g^(-1),superior rate performance(112.6 mAh g^(-1)at 1.0 A g^(-1)),and outstanding cyclic stability at various current densities.

Carbonaceous and nitrogenous disinfection by-product formation in the surface and ground water treatment plants using Yellow River as water source

This work investigated the formation of carbonaceous and nitrogenous disinfection by-products （C-DBPs, N-DBPs） upon chlorination of water samples collected from a surface water and a ground water treatment plant （SWTP and GWTP） where the conventional treatment processes, i.e., coagulation, sedimentation, and filtration were employed. Twenty DBPs, including four trihalomethanes, nine haloacetic acids, seven N-DBPs （dichloroacetamide, trichloroacetamide, dichloroacetonitrile, trichloroacetonitrile, bromochloroace- tonitrile, dibromoacetonitrile and trichloronitromethane）, and eight volatile chlorinated compounds （dichloromethane （DCM）, 1,2-dichloroethane, tetrachloroethylene, chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene and 1,2,4- trichlorobenzene） were detected in the two WTPs. The concentrations of these contaminants were all below their corresponding maximum contamination levels （MCLs） regulated by the Standards for Drinking Water Quality of China （GB5749-2006） except for DCM （17.1 ~tg/L detected vs. 20 μg/L MCL）. The SWTP had much higher concentrations of DBPs detected in the treated water as well as the DBP formation potentials tested in the filtered water than the GWTP, probably because more precursors （e.g., dissolved organic carbon, dissolved organic nitrogen） were present in the water source of the SWTE

Asymmetric epigenome maps of subgenomes reveal imbalanced transcription and distinct evolutionary trends in Brassica napus

The complexity of the epigenome landscape and transcriptional regulation is significantly increased during plant polyploidization,which drives genome evolution and contributes to the increased adaptability to diverse environments.However,a comprehensive epigenome map of Brassica napus is still unavailable.In this study,we performed integrative analysis of five histone modifications,RNA polymerase Ⅱ CCU-pancy,DNA methylation,and transcriptomes in two B.napus lines(2063A and B409),and established global maps of regulatory elements,chromatin states,and their dynamics for the whole genome(including the An and Cn subgenomes)in four tissue types(young leaf,flower bud,silique,and root)of these two lines.Approximately 65.8% of the genome was annotated with different epigenomic signals.Compared with the Cn subgenome,the An subgenome possesses a higher level of active epigenetic marks and lower level of repressive epigenetic marks.Genes from subgenome-unique regions contribute to the major differences between the An and Cn subgenomes.Asymmetric histone modifications between homeologous gene pairs reflect their biased expression patterns.We identified a novel bivalent chromatin state(with H3K4me1 and H3K27me3)in B.napus that is associated with tissue-specific gene expression.Furthermore,we observed that different types of duplicated genes have discrepant patterns of histone modification and DNA methylation levels.Collectively,our findings provide a valuable epigenetic resource for allopolyploid plants.

NODAL secreted by male germ cells regulates the proliferation and function of human Sertoli cells from obstructive azoospermia and nonobstructive azoospermia patients

This study was designed to explore the regulatory effects of male germ cell secreting factor NODAL on Sertoli cell fate decisions from obstructive azoospermia （OA） and nonobstructive azoospermia （NOA） patients. Human Sertoli cells and male germ cells were isolated using two-step enzymatic digestion and SATPUT from testes of azoospermia patients. Expression of NODAL and its multiple receptors in human Sertoli cells and male germ cells were characterized by reverse transcription-polymerase chain reaction （RT-PCRI and immunochemistry. Human recombinant NODAL and its receptor inhibitor SB431542 were employed to probe their effect on the proliferation of Sertoli cells using the CCK-8 assay. Quantitative PCR and Western blots were utilized to assess the expression of Sertoli cell functional genes and proteins. NODAL was found to be expressed in male germ cells but not in Sertoli cells, whereas its receptors ALK4, ALK7, and ACTR-IIB were detected in Sertoli cells and germ cells, suggesting that NODAL plays a regulatory role in Sertoli cells and germ cells via a paracrine and autocrine pathway, respectively. Human recombinant NODAL could promote the proliferation of human Sertoli cells. The expression of cell cycle regulators, including CYCLIN A, CYCLIN D1 and CYCLIN E, was not remarkably affected by NODAL signaling. NODAL enhanced the expression of essential growth factors, including GDNF, SCF, and BMP4, whereas SB431542 decreased their levels. There was not homogeneity of genes changes by NODAL treatment in Sertoli cells from OA and Sertoli cell-only syndrome （SCO） patients. Collectively, this study demonstrates that NODAL produced by human male germ cells regulates proliferation and numerous gene expression of Sertoli cells.

Confinedly implanting Fe_(3)O_(4) nanoclusters on MoS_(2) nanosheets to tailor electromagnetic properties for excellent multi-bands microwave absorption

High efficiency microwave absorption(MA)materials with tunable electromagnetic(EM)features have been highly sought.However,it is still a challenge to achieve multi-bands absorption performance by simple optimizing the chemical composition of MA materials.Herein,a simple solvothermal method was used to embed magnetic Fe_(3)O_(4) nanodusters on MoS2 nanosheets,in which magnetic nanodusters weme quantitatively customized More importantly,the MA frequency and MA properties of the material are highly tailored,and multi-bands absorption is achieved.The minimum reflection loss(RL)of Fe_(3)O_(4)/MoS_(2) composite reaches-87.24 dB and is about 4 times more than pure MoS_(2) nanosheets.The effective ab-sorption bandwidth reaches 5.52 GHz(≤-10 dB).These desirable properties result from the introduction of appropriate magnetic Fe_(3)O_(4) nanoclusters,which provide optimal synegistic effect of dielectric and magnetic losses.This result provides a feasible idea for designing high efficiency MA materials with tunable EM features in the future.

Inspecting design rules of metal-nitrogen-carbon catalysts for electrochemical CO_(2)reduction reaction:From a data science perspective

The development of inexpensive metal-nitrogen-carbon(M-N-C)catalysts for electrochemical CO_(2)reduction reaction(CO_(2)RR)on an industrial scale has come to a standstill.Although the number of related studies and reviews has grown fast,the complexity of the M-N-C composite has limited researchers to focus on only a few variables and carry out sluggish trial-and-error optimizations in their studies.As a result,the conclusions are drawn only by artificial analysis based on a few orthogonal experimental results.To obtain more general design strategies,we have innovatively introduced machine learning(ML)into this field to address this bottleneck.A standard workflow that comprehensively utilizes different ML algorithms and black-box interpretation methods is proposed for this purpose.Besides predicting CO_(2)RR performance metrics for M-N-C catalysts,such as maximum faradaic efficiency with great accuracy,the ML models have also indicated simple and clear design strategies that would guide future exploration from a data science perspective.Besides,we have also demonstrated the potential of the models in guiding the development of new material systems.We thereby believe that the new research paradigm proposed may accelerate the development of this field soon.

Analytical solution of ground-borne vibration due to a spatially periodic harmonic moving load in a tunnel embedded in layered soil

In this study,we propose a novel coupled periodic tunnel–soil analytical model for predicting ground-borne vibrations caused by vibration sources in tunnels.The problem of a multilayered soil overlying a semi-infinite half-space was solved using the transfer matrix method.To account for the interactions between the soil layer and tunnel structure,the transformation characteristics between cylindrical waves and plane waves were considered and used to convert the corresponding wave potentials into forms in terms of the Cartesian or cylindrical coordinate system.The induced ground-borne vibration was obtained analytically by applying a spatially periodic harmonic moving load to the tunnel invert.The accuracy and efficiency of the proposed model were verified by comparing the results under a moving constant and harmonic load with those from previous studies.Subsequently,the response characteristics under a spatially periodic harmonic moving load were identified,and the effects of a wide range of factors on the responses were systematically investigated.The numerical results showed that moving and Doppler effects can be caused by a spatially periodic harmonic moving load.The critical frequency and frequency bandwidth of the response are affected by the load type,frequency,velocity,and wavenumber in one periodicity length.Increasing the tunnel depth is an efficient way to reduce ground-borne vibrations.The effect of vibration amplification on the free surface should be considered to avoid excessive vibration levels that disturb residents.

多重限域几何中的化学键助力Bi_(2)Se_(3)基转换-合金负极材料实现优异的钠离子储存

转换-合金基材料被认为是低成本钠离子电池最有价值的负极之一,然而大的体积变化、差的电化学动力学行为成为了阻碍其应用的关键科学问题.在本文中,超薄纳米片自组装Bi_(2)Se_(3)纳米花通过强健的C-O-Bi化学键合作用被锚定在还原氧化石墨烯(rGO)上,并被氮掺杂碳纳米层(NC)紧密地包裹,构筑出的Bi_(2)Se_(3)@rGO@NC复合材料被用于钠离子电池负极.物理化学限域几何有助于通过容纳大的晶格应变而获得优异的电极完整性,同时通过消除带隙并降低钠离子扩散势垒促进良好的动力学过程.钠离子的插入/脱出是通过以铋离子为氧化还原位点的转换-合金双重反应机制进行的,其中每个分子式单元可实现12个电子的传输(Bi_(2)Se_(3)+12Na^(+)+12e^(−)↔2Na_(3)Bi+3Na_(2)Se).因此Bi_(2)Se_(3)@rGO@NC电极在50 mA g^(-1)电流密度下呈现出高达288.4 mA h g^(-1)的首次充电容量,同时具有超过1000次的超长循环寿命与优异的倍率性能(在5.0 A g^(-1)电流密度下容量为119.9 mA h g^(-1)).本工作为转换-合金负极的系统研究奠定了基础,为钠离子电池电化学反应机理的阐明提供了新的思路.

T形截面钢压杆几何初始缺陷测量方法研究

几何初始缺陷是影响钢压杆整体稳定承载力的重要缺陷因素之一。T形截面钢压杆的常见几何初始缺陷包括构件初弯曲、荷载初偏心及构件初扭转。在压杆整体稳定承载力研究中,为了更加精确便捷地测量出构件的几何初始缺陷大小,基于传统弹性稳定理论,利用T形截面钢压杆几何初始缺陷与荷载、截面应变、侧移及扭转等参数之间的关系,推导出几何初始缺陷的计算式,提出利用压杆弹性阶段的荷载与变形关系获得几何初始缺陷的参数反推测量法。借助ANSYS建立具有几何初始缺陷的T形截面钢压杆三维模型,并对其进行几何非线性分析,将模型初设的几何缺陷值与按照新方法计算所得的结果进行对比,验证所提出的几何初始缺陷计算式的正确性。结合T形截面钢压杆整体稳定承载力试验,获得弹性阶段荷载、截面应变、侧移及扭转实测值,基于新提出的参数反推测量法,计算钢压杆实际几何初始缺陷大小,并将结果与传统光学仪器测量法获得的结果进行对比,验证参数反推测量法的正确性。分析结果表明:T形截面钢压杆几何初始缺陷的参数反推测量法具有正确性和可行性;该方法不需要另设测量设备、可减小人为测量误差,具有高效性和精确性;同时,该方法考虑了实际压杆在整体稳定承载力试验过程中,因端部约束作用影响而产生的杆件临界力大小,不仅可获得构件初弯曲及荷载初偏心之和,还可获得构件初扭转缺陷值。基于新参数反推测量法获得的几何初始缺陷值,可作为初参数直接引入后续的T形截面钢压杆整体稳定承载力分析,为钢压杆整体稳定承载力研究提供重要参考。

鸡源CD40L基因克隆、蛋白表达及生物活性检测

为获得鸡源CD40L(chCD40L)蛋白,以鸡脾细胞制备cDNA并以之为模板扩增chCD40L基因,构建pFastBac-chCD40L供体重组质粒,转化感受态细胞DH10Bac,通过筛选及鉴定获得Bacmid-chCD40L重组质粒,转入真核表达系统sf9昆虫细胞进行蛋白表达与纯化,获得His-chCD40L蛋白。此外,构建pQM01-chCD40L质粒,转染HEK293T细胞进行蛋白表达与纯化,获得Strep-chCD40L蛋白。亲和层析纯化的chCD40L蛋白浓度为0.01 mg/mL。为检测chCD40L蛋白的生物活性,分离和培养3周龄SPF雏鸡的法氏囊组织原代细胞,将chCD40L加入细胞培养液刺激细胞增殖,通过Western blotting试验、间接免疫荧光试验、流式细胞术检测,发现该蛋白能够与法氏囊B淋巴细胞表面的CD40结合,说明chCD40L具有生物活性。成功获得chCD40L蛋白,为原代B淋巴细胞体外培养及IBDV野毒分离与诊断奠定了基础。

Metro train-induced vibrations on historic buildings in Chengdu,China

In this paper, the vibration influence on a monument caused by Chengdu Subway Line 2 is analyzed. Due to its elaborate and unique design, both structural and architectural damages should be avoided. First, the allowable root mean square （RMS） velocity at the foundation of the monument is derived and a site measurement is performed to obtain the background vibrations induced by road traffic. In addition, a train-track coupled model and 3D tunnel-soil-structure coupled finite element models are built to predict the dynamic response of the monument. Prediction models are checked by site measurement in Beijing Subway Line 5. Different kinds of fasteners and train speeds are compared and discussed as well. Results show that： （1） At a train speed of 72 km/h, all the traffic vibrations exceed the low limit no matter what kind of fastener is used, which is mainly due to the contribution of road traffic. Slowing down train speeds can cause effective vibration attenuation; （2） Vibrations drop dramatically with the train speed from 65 to 58 km/h. When the train speed is lower than 58 krn/h, vibrations are lower than allowable value even if the contribution of road traffic is considered.

Novel double-layer Silastic testicular prosthesis with controlled release of testosterone in vitro, and its effects on castrated rats

Testicular prostheses have been used to deal with anorchia for nearly 80 years. Here, we evaluated a novel testicular prosthesis that can controllably release hormones to maintain physiological levels of testosterone in vivo for a long time. Silastic testicular prostheses with controlled release of testosterone （STPT） with different dosages of testosterone undecanoate （TU） were prepared and implanted into castrated Sprague-Dawley rats. TU oil was applied by oral administration to a separate group of castrated rats. Castrated untreated and sham-operated groups were used as controls. Serum samples from every group were collected to measure the levels of testosterone （T）, follicle-stimulating hormone and luteinizing hormone （LH）. Maximum intracavernous penile pressure （ICPmax） was recorded. The prostates and seminal vesicles were weighed and subjected to histology, and a terminal dexynucleotidyl transferase-mediated UTP nick end labeling （TUNEL） assay was used to evaluate apoptosis. Our results revealed that the weights of these tissues and the levels of T and LH showed significant statistical differences in the oral administration and TU replacement groups compared with the castrated group （P 〈 0.05）. Compared with the sham-operated group, the ICPmax, histology and TUNEL staining for apoptosis, showed no significant differences in the hormone replacement groups implanted with medium and high doses of STPT. Our results suggested that this new STPT could release TU stably through its double semi-permeable membranes with excellent biocompatibility. The study provides a new approach for testosterone replacement therapy.

CO_(2)捕集及电催化还原制甲酸研究进展

CO_(2)捕集与CO_(2)电催化还原技术是减少碳排放、提高碳的可再生循环利用率的重要途径.两种技术既独立存在,又可以作为碳循环周期中的上下环节相互结合,即先捕集并提纯混合气中的CO_(2),然后将收集到的高纯度CO_(2)进行电催化还原反应,将其进一步转化为更有用的化学品.本文首先总结了CO_(2)捕集技术的研究现状,然后考虑到甲酸作为目前经济和技术上最具潜力的还原产物,调研并汇总了近年来在CO_(2)电还原制甲酸领域中关于高效电催化剂的制备和反应器件设计方面取得的研究进展.针对两种技术的研究现状,最后提出加快和开发新型碳捕集与利用技术,开发低成本、高效、稳定的电催化剂和设计具有低欧姆电阻、高转化能效的反应器等可以作为未来的研究重点和发展方向.