树脂对碳纤维/玻璃纤维层间混杂复合材料湿态弯曲特性影响

为了探究树脂基体对相同铺层方式下碳纤维/玻璃纤维层间混杂复合材料(碳/玻体积混杂比为1.86/1)干态、湿态(100℃水煮2 h)弯曲特性的影响,首先对环氧树脂和乙烯基树脂浇铸体试样分别开展了耐水性加速老化试验,并对两种树脂浇铸体试样在每个老化试验周期下分别开展剩余弯曲特性试验;然后对碳/玻层间混杂复合材料开展干、湿态...     

高效实用的板带变形求解方法

针对轧件弹塑性变形与轧辊弹性变形计算分离的弊端,用轧制力分布系数将这2个模型结合起来,并解决了此2个模型之间的耦合问题.理论计算结果在1700mm热连轧机组样品进行验证,理论和实践两者符合较好.     

基于软件工程的拉深模CAD系统的研究

以软件工程学的原理对拉深模CAD系统进行结构化分析、结构化设计和结构化程序设计。利用该方法编制的拉深模CAD系统结构化程度高 ,通用性强 ,便于修改和维护     

小型化低温共烧陶瓷片式天线研究

提出一种适用于蓝牙频段的小型化全向天线。该天线采用低温共烧陶瓷(LTCC)技术,将金属导线按曲折走线的方式内埋于LTCC微波陶瓷介质中,上下层导线通过通孔实现互连,有效缩小了体积,并保护了天线辐射单元以提高可靠性。通过分析天线三维结构,提取了天线等效电路模型,电磁场仿真与电路仿真结果基本一致。与传统天线相比,该天线具有全向性好、带宽大、性能稳定等优点,且外形短小紧凑,适用于对天线尺度要求比较苛刻的各种高灵敏度、低剖面的无线通信收发模块及移动通信终端。     

限时点到多点跨数据中心传输的多源树调度算法

随着各种云应用的数据规模的增大,越来越多的云服务提供商开始关注跨数据中心的大数据块传输(bulk transfer)。跨数据中心的大数据块传输面临的主要挑战是:如何找到最佳的资源调度算法,在用户指定的时限内,用最少的传输资源将用户的数据传输到指定的地点。文中设计了一种有效的带传输时限(transfer deadlines)的、点到多点(Point-to-MultiPoint,P2MP)的跨数据中心数据传输调度算法MSTB(Multi-Source Tree-Based algorithm)。在多源机制和多播转发树的帮助下,MSTB表现得比现有的最优方法更好。仿真实验结果表明,MSTB可以在保证低传输完成时间和低计算复杂度的同时,增加最高达91%的传输请求接受数,增加最高达54%的有效吞吐量。     

小区集中供热系统循环水泵电耗实测分析

对6个小区集中供热系统的17台循环水泵的电耗、实际运行效率、循环流量进行了实测,分析了造成小区集中供热系统输配能耗较高的原因,结合实例计算了各种能耗损失的大小和所占比例,给出了小区集中供热系统实际需求耗电量指标.     

Spatiotemporalized Hydrogel Microspheres Promote Vascularized Osteogenesis via Ultrasound Oxygen Delivery

Disturbance of spatiotemporal oxygen balance is the main cause of delayed healing or nonhealing of large bone defects. The accurate administration of oxygen to regulate disruptions in the spatiotemporal oxygen equilibrium during 9 h of hypoxia is imperative for bone tissue regeneration. Herein, oxygen-loaded nanobubbles prepared by double emulsification are successfully embedded in GelMA/HepMA microsphere macromolecular meshwork by microfluidic techniques, and a spatiotemporalized hydrogel microsphere is constructed by noncovalently binding bone morphogenetic protein 2 (BMP-2). The spatiotemporalized hydrogel microspheres precisely “remote control” oxygen release by ultrasound in vitro 9 h after bone injury to regulate spatiotemporal oxygen homeostasis disorder, maintain a high level of vascular endothelial growth factor (VEGF) expression, and accelerate bone repair. The spatiotemporalized hydrogel microspheres possess good oxygen-carrying capacity and ultrasonic responsiveness, and the oxygen concentration increases to 1.63, 1.95, 2.11, and 2.29 times under the ultrasound action at different intensities of 1, 2, 3, and 4 W, respectively, providing the conditions for the precise regulation of spatiotemporal oxygen balance disorder by ultrasound. In the in vitro hypoxia model and in vivo rat femoral defect model, the spatiotemporal hydrogel microspheres show good vascularization and osteogenesis capabilities, which provide a new strategy for the clinical treatment of large bone defects.     

Inch-Size Achiral Perovskite Single Crystals for Distinguishing Circularly Polarized Light with A Large Asymmetry Factor

Circularly polarized light (CPL) detection has sparked the booming interest for versatile chiral-optoelectronic and spintronic devices. For practical device applications, a large asymmetry factor is required to distinguish the handedness of incent light. However, for most chiral CPL active candidates, the difference in optical density or absorption anisotropy is quite subtle under CPL illumination, resulting in a relatively low asymmetry factor (usually ≤ 0.2). Up to date, it remains extremely challenging to achieve CPL response in the achiral crystals. Inch-size achiral perovskite-type crystals of (IBA)₂(EA)₂Pb₃I₁₀ (IBA = 4-isopropylbenzylammonium, EA = ethylammonium), which holds a promise to distinguish CPL with a large asymmetry factor up to ≈0.56 at 405 nm is presented here. This figure-of-merit is comparable or even superior than most of those chiral counterparts. Further First-principles calculations disclose such CPL-active behaviors of (IBA)₂(EA)₂Pb₃I₁₀ are associated with the splitting of its band spin-degeneracy, induced by the breaking of inversion symmetry and spin-orbital coupling (SOC) effects. As far as it is known, the structural origin of CPL-activities of (IBA)₂(EA)₂Pb₃I₁₀ is completely distinctive from the conventional chiral family, which paves a promising pathway to explore new candidates toward high-performance CPL detection.     

Interfacial Charge Transfer Bridge Prolongs Carrier Recombination Lifetimes of CoFe Metal-Thiolate Framework/Hematite Photoanode for Water Oxidation

Constructing heterostructural photoanodes is attractive for elevating the photoelectrochemical (PEC) performance, however, it is a long-standing challenge to achieve highly efficient interfacial charge transfer. Herein, a CoFe metal-thiolate framework (CoFe MTF)/Fe₂O₃ photoanode connected by an interfacial Fe─O─N/S bond is designed to modulate the behavior of charge carriers and improve water oxidation performance. It is disclosed that this interfacial bond functions as a direct charge transfer bridge between shallow trap states of Fe₂O₃ and CoFe MTF, leading to prolonged carrier recombination lifetimes (85 ns for CoFe MTF/Fe₂O₃ compared to 37 ns for Fe₂O₃) and enhanced charge transfer efficiency. Alternatively, a robust interfacial electric field is established in the CoFe MTF/Fe₂O₃ p–n heterojunction, facilitating efficient charge transfer. As expected, the CoFe MTF/Fe₂O₃ photoanode exhibits significant enhancement in water oxidation, resulting in a three-fold increase in photocurrent density compared to pristine Fe₂O₃. This study highlights the significance of designing interfacially bonded heterostructural photoelectrodes to regulate the transfer characters of charge carriers.     

试析基于4G通信技术的无线网络安全通信

伴随着科学技术的持续性发展,网络与通信技术均得到了显著的发展,目前来看4G通信技术已经相对比较成熟,在网络安全防护方面的技术水平也相对比较理想。对此,为了进一步提高4G通讯技术应用水平,本文简要分析基于4G通信技术的无线网络安全通信,希望可以为相关工作者提供理论帮助。