摘要：To obtain a small-angle monoenergetic neutron source,a shielding collimator device is designed for the neutron source generated by a neutron *** device is divided into the collimator and the capture *** collimator is made of three layers of stainless steel and borated polyethylene and is used to constrain neutrons in a small *** capture cave is used to increase the number of times neutron inelastic scattering occurs in the opposite direction of the radiation field,thereby reducing the proportion of scattered neutrons in the radiation *** thickness,aperture size,and the optimum structure of the capture cave were simulated using *** design features a neutron emission angle within a range of 3° and neutron fluxes in the radiation field,which are higher by two orders of magnitude than those outside the radiation *** research has practical value for the generation of monoenergetic small-angle neutron sources and neutron applications.

摘要：为了探究固化盾构渣土应用于道路工程建设的可行性,以南京地铁盾构渣土为研究对象,利用自主研制的绿色高分子复合固化剂固化盾构渣土。开展无侧限抗压强度、直剪试验、加州承载比(California bearing ratio, CBR)、回弹模量以及冻融循环试验探究了固化剂掺量和养护龄期对盾构渣土路用性能指标的影响,并对固化土试样进行电镜扫描和X射线衍射试验来探究其微观特征和固化机理。试验结果表明:复合固化剂能有效提升固化土强度,且随着固化剂掺量和养护龄期的增加,固化土强度也随之提高;固化土的CBR值和回弹模量也随固化剂掺量提高而显著提升,能够很好地满足《公路路基设计规范》(JTG D30—2015)和《公路沥青路面设计规范》(JTG D50—2017)中有关路用性能指标的要求;盾构渣土的抗冻融稳定性经固化处理后可有效地改善,固化土冻融前后强度和质量损失分别在20%和1%以下,抗冻性能指标均达到了规范要求;固化剂加入盾构渣土后其中的高分子组分会吸水溶解并与土体中的矿物离子发生静电螯合作用,在初步降低土体含水率的同时也促进了土颗粒之间的胶结团聚,与此同时,固化剂的其他组分会发生水化反应形成水化硅酸钙凝胶(C-S-H)和钙矾石(AFt)等物质,这些物质填充在土体孔隙,使土体结构变得更加致密,土体的强度得到显著提升。

摘要：在宁夏中卫连续30余年压砂首次退砂的土地进行种植试验,以当地主栽的西瓜品种‘金城5号’为试验材料进行膜下滴灌栽培。灌溉量设置3个水平:常规灌溉(中水W2,3 000 m^(3)·hm^(-2))、常规灌溉加灌20%(高水W3,3 600 m^(3)·hm^(-2))、常规灌溉减灌20%(低水W1,2 400 m^(3)·hm^(-2))和5个施氮水平:N0(0 kg·hm^(-2))、N1(80 kg·hm^(-2))、N2(160 kg·hm^(-2))、N3(240 kg·hm^(-2))、N4(320 kg·hm^(-2)),采用完全随机区组设计,共15个处理。结果表明:高水处理下,西瓜膨瓜期蔓长在5种氮水平下比中水处理分别提高9.15%、8.41%、8.69%、11.58%和12.00%;中水处理下,伸蔓期、开花坐果期和膨瓜期N2的西瓜蔓长较N0处理提高5.42%~7.13%;N2水平下,3个时期中水较低水处理西瓜蔓长提高2.71%~16.67%。低水处理和高水处理的西瓜可溶性总糖含量分别较中水处理降低13.09%~60.21%和6.69%~9.14%;中水和低水处理下N2处理的可溶性总糖含量较N0分别提高21.19%和70.47%,高水处理下N3处理的可溶性总糖含量较N0提高8.25%。在施氮量相同时,灌水对植株生长的促进作用表现为W3>W2>W1,而对西瓜品质的提高作用表现为W2>W3>W1。当灌溉水平为3 600 m^(3)·hm^(-2)、施氮量为240 kg·hm^(-2)时产量最高,为64 299.67 kg·hm^(-2)。土壤有机质含量和脲酶活性在T4处理下达到最高;土壤全氮含量不会随着施氮量的增加逐渐升高,但会随着灌溉水平提高逐渐升高;在相同灌溉水平下,N1、N2、N3和N4条件下土壤铵态氮含量分别较N0处理平均提高11.90%、16.87%、24.58%和46.39%。提高灌溉量有利于提高氮肥偏生产力,但会使水分利用效率降低,施氮量从N0增加到N4时,W1灌溉水平下的水分利用效率最高。当灌溉水平为3 600 m^(3)·hm^(-2)、施氮量为240 kg·hm^(-2)时,西瓜生长、产量和水氮利用效率最佳。

摘要：A concept of hierarchical stiffened shell is proposed in this study, aiming at reducing the imperfection sen- sitivity without adding additional weight. Hierarchical stiffened shell is composed of major stiffeners and minor stiff- eners, and the minor stiffeners are generally distributed between adjacent major stiffeners. For various types of geo- metric imperfections, e.g., eigenmode-shape imperfections, hierarchical stiffened shell shows significantly low imper- fection sensitivity compared to traditional stiffened shell. Furthermore, a surrogate-based optimization framework is proposed to search for the hierarchical optimum design. Then, two optimum designs based on two different opti- mization objectives （including the critical buckling load and the weighted sum of collapse loads of geometrically imperfect shells with small- and large-amplitude imperfections） are compared and discussed in detail. The illustrative example demonstrates the inherent superiority of hierarchical stiffened shells in resisting imperfections and the effectiveness of the proposed framework. Moreover, the decrease of imperfection sensitivity can finally be converted into a decrease of structural weight, which is particularly important in the development of large-diameter launch vehicles.

摘要：随着NEG并网功率不断增大和负荷日益多元化,如何快速协调配网系统源荷功率平衡,实现新能源最大化消纳,已成为亟需解决的问题。为此,首先分析了配网网格特点;其次设计了一种基于配网网格NEG与LF信息的智能终端,给出了其功能、整体构成、供电电源、信息采集与传输方案以及源荷协调策略,以协调网格内源荷功率平衡;最后研制了相关产品,重点做了网格内源荷功率协调测试,并与目前方案进行了对比。结果表明,文中所设计智能终端能够对网格内源荷功率进行可靠协调,实现NEG最大化利用和多方信息共享,推广应用价值高。

摘要：Because ring-stiffened cylindrical shell structures have many merits, they are widely used in many areas. However, as the strength of steel increase continuously, ensuring of the structure stability is becoming more and more important. Therefore, it is necessary to carry on a more particular analysis. Based on the understanding and analysis of the characteristics of stability for a ring-stiffened cylindrical shell under uniform external pressure and under external single pressure, the characteristics under different cross uniform external pressures are analyzed, and the regularity of it is also gotten. The curve of stability given various geometrical parameters under different cross uniform external pressures is protracted by the analysis of the theory. The conclusion not only improves the theory structural mechanics, it also was important effects on engineering calculation and design.

摘要：The integration and accommodation of the wind and solar energy pose great challenges on today’s power system operation due to the intermittent nature and volatility of the wind and solar *** efficient large-scale electrical energy storage is one of the most effective and economical solutions to those *** the comprehensive review of the existing storage technologies,this paper proposes an overall design scheme for the Non-supplementary Fired Compressed Air Energy Storage(NFCAES)system,including system design,modeling and efficiency assessment,as well as protection and ***,the design principles of the multistage regenerative,*** recovery system which is used to fully recycle and utilize the waste heat from compression are provided,so as the overall system efficiency evaluation *** paper theoretically ascertains the storage decoupling rules in the potential and internal energy of molecular compressed air and reveals the conversion mechanism of gas,heat,power,electricity and other forms of *** this basis,a 500-k W physical simulation system of CAES system(TICC-500,Tsinghua-IPCCAS-CEPRI-CAES)is built,which passed a system-wide 420-k W load power generation test with less pollution and zero carbon ***,the multi-form energy conversion of multi-stage regenerative CAES and storage efficiency is verified,especially its incomparable superiority in solving the uncertainty problem in wind and solar power ***,the propaganda and application scenario of the CAES system in China is introduced.

摘要：通信基础设施建设作为国家“新基建”的重要组成部分,其产业链供应链安全至关重要。近年来,全球贸易摩擦不断、地缘冲突时有发生,导致通信产业关键零部件被“卡脖子”,通信产业链供应链的安全稳定面临挑战。为提高通信产业链供应链韧性与安全,文章对通信产业链供应链形势和现状进行了分析,提出结论:国家和行业层面要健全标准、能力补齐以及数智基础加固,企业层面要坚定发展理念与多措施保障稳定,提升我国通信产业链供应链韧性与安全。

摘要：立足典型低空场景的业务需求,分析了5G低空覆盖所需的信号覆盖水平,并基于典型5G中频设备天线性能,参考3GPP推荐的低空传播模型,立体分层地计算分析了典型3扇区基站用于低空覆盖时的信号覆盖水平。评估了各类设备的低空覆盖能力以及适用的部署场景和最佳部署仰角,为5G低空通信网络部署提供了可借鉴的方案。

摘要：A series of tri-substituted chiral pyrrolidin-2-one derivatives have been designed and synthesized as CC chemokine receptor 4 （CCR4） antagonists. The structure of CCR4 was built by homology modeling. Asymmetric synthesis was applied to synthesize the R,R configuration chiral pyrrolidin-2-one scaffold. The stereoisomeric con- figurations of the compounds were identified by 2D I H-~H COSY spectroscopy and 1D NOESY spectroscopy. This method was more economical and convenient than traditional X-ray single crystal diffraction. In addition, the inter- actions between these compounds and the N-terminal extracellular tail of CCR4 were studied using capillary zone electrophoresis. The CCR4 chemotaxis inhibition effect was tested in CCR4-transfected HEK293 cells. Several compounds showed potent activities as CCR4 antagonists. Among these compounds, lc is the most active one. Its apparent binding constant of CZE experiment result is （1.569±0.11）× 10s L·mol ^-1, and its percentage inhibition of the HEK293/CCR4 cells migration with the concentration of I gmol·L ^-1 in DMSO is 59%. And compound If has slightly higher affinity to N-terminal of CCR4 according to its apparent binding constant than lb because of the in- troduced ester linkage. Further studies on the mechanism of these compounds are in progress.