基于支持向量回归的腔体滤波器机电耦合建模与优化

为了提高装配后的滤波器电性能和成品率,该文提出了一种基于支持向量回归的腔体滤波器机电耦合建模和优化方法。该方法根据工程中积累的经验数据,首先应用改进的多核线性规划支持向量回归算法建立了制造精度对滤波器电性能影响的机电耦合模型,然后应用此模型优化了滤波器的制造精度,从而获得了最优的机械结构尺寸。实际滤波器的实验结果验证了该方法的有效性。该方法可用于批量生产的腔体滤波器的计算机辅助制造系统中。     

基于自适应网格的隐私空间分割方法

基于网格与差分隐私保护的空间数据分割得到了研究者的广泛关注,空间数据的大小、数据的偏斜性以及拉普拉斯噪音的多少直接制约着空间分割的精度.针对现有基于网格分割方法难以有效兼顾大规模空间数据、数据偏斜性与噪音量的不足,提出了一种基于伯努利随机抽样技术的3层自适应网格分割(sampling-based three-layer adaptive grid decomposition, STAG)方法,该方法利用满足差分隐私的抽样技术抽取空间数据点作为分割对象.根据查询粒度的不同,首先在中间层利用指数机制与高通滤波过滤掉小于阈值的网格单元,然后利用Down-Split方法继续细分大于阈值的网格单元.对于那些小于阈值且连接的单元格,利用Up-Merge操作对这些单元进行最优化重组,形成粗粒度的网格单元.STAG与UG(uniform grid),AG(adaptive grid),Kd-Stand(kd-tree-based standard method),Kd-Hybrid(kd-tree-based hybrid method)在真实的大规模空间数据集上实验结果表明：其分割精度以及响应范围查询效果优于同类算法.     

基于在线聚类的协同作弊团体识别方法

针对大规模服务计算环境中聚集反馈、协同作弊和虚假评价等问题,通过融合在线聚类与共谋欺骗检测技术,提出了一种支持大规模服务可信度分析的在线协同作弊用户发现方法.首先,根据大规模服务系统日志中用户反馈评分信息,综合考虑大规模服务计算的大数据特性问题,设计了一种新颖的基于改进更新规则的在线KMeans聚类算法：在基于随机梯度法的在线聚类算法的基础上,采用了一种改进的基于小批量学习的在线聚类方法;并且,通过自动修正权重的聚类分组方差计算,进行递减增量优化,提高了在线KMeans算法的聚类质量,同时保证了聚类算法的时间效率;然后,充分考虑了协同作弊团体的同谋行为特征和协同攻击现象,利用聚类分组的性质和同谋团体异常性的特征,检测出协同作弊团体.仿真实验结果表明：提出的基于在线聚类的协同作弊团体识别方法具有良好时间性能,有效地解决了大规模服务计算中虚假反馈的问题.     

中国建筑企业国际化绩效评价体系研究（连载）

随着中国的入世和近年来国家“走出去”战略的实施,已经促使越来越多的中国建筑企业走向国际市场。为使企业能够更好的实现国际化发展,有必要对这些企业海外经营绩效进行评价,以及时的发现他们在经营中存在的不足和偏差,从而为企业制定科学而有效的发展战略提供参考和指导,因此,建立一套科学而适用的国际化绩效评价体系就尤为重要。本文在总结以往理论研究的基础上,参考平衡计分卡的考核框架体系并结合了建筑产业的持点,构建出一套能够适用于中国建筑企业的国际化绩效评价体系。最后,通过一个企业实际的应用案例来展示该体系的可行性与适用性。从而,本研究为建筑企业的国际化经营提供了一套科学的理论指导体系。     

What is system wide information management (SWIM)?

为了解决广域信息管理(system wide information management, SWIM)信息安全问题,根据SWIM面向服务的系统架构 (service-oriented architecture, SOA)的特点,设计SWIM的访问策略,提出了一种基于属性密码(attribute-based encryption, ABE)的授权方法. 该方法根据SWIM访问结构中分布性、异构性和动态性的特点,采用密文访问策略 (cipher policy- attribute based encryption, CP-ABE)实现. 在模拟环境中对该方法进行仿真实验和安全性分析,实验结果表明:该方法支持SWIM航空用户细粒度的授权,降低了SWIM授权管理的复杂度,提高了SWIM系统的安全性.

     

镁合金表面磁控溅射沉积铝膜的力学性能

采用直流磁控溅射法在镁合金上沉积铝膜,在高真空下对铝膜进行加热后处理.用X射线衍射仪(XRD)分析膜层为纯铝多晶态,扫描电子显微镜(SEM)观察铝膜晶粒细小.采用纳米压痕/划痕仪对铝膜的厚度、临界附着力、硬度和弹性模量进行了测试,并且用辉光放电光谱仪(GDS)测试了镁合金表面铝膜的成分和性能随薄膜深度的分布.结果表明,铝膜的厚度随后处理温度的升高而降低,其表面硬度和弹性模量高于镁合金基体并且随深度增加而逐渐降低.铝膜与镁合金基体间存在一个过渡层,结合良好且表现出一定的弹塑性能,有利于镁合金表面的防护.     

Toward a Nanoscale-Defect-Free Ni-Rich Layered Oxide Cathode Through Regulated Pore Evolution for Long-Lifespan Li Rechargeable Batteries

Ni-rich layered oxides are envisioned as the most promising cathode materials for next-generation lithium-ion batteries; however, their practical adoption is plagued by fast capacity decay originating from chemo-mechanical degradation. The intrinsic chemical–mechanical instability, inherited from atomic- and nanoscale defects generated during synthesis, is not yet resolved. Here, atomic- and nanoscale structural evolution during solid-state synthesis of Ni-rich layered cathode, Li[Ni_0.92Co_0.03Mn_0.05]O₂, is investigated using combined X-ray/neutron scattering and electron/X-ray microscopy. The multiscale analyses demonstrate the intertwined correlation between phase transition and microstructural evolution, with atomic-scale defects derived from the decomposition of precursors leading to the creation of intra/inter-granular pores. The nucleation and coalescence mechanism of pore defects during the synthesis of Ni-rich layered cathodes are quantitatively revealed. Furthermore, a modified synthetic route is proposed to effectively circumvent the formation of nanoscale defects in Ni-rich layered cathodes by facilitating uniform synthetic reactions, resulting in superior electrochemical and microstructural stability.     

Epitaxial Growth of 1D Te/2D MoSe2 Mixed-Dimensional Heterostructures for High-Efficient Self-Powered Photodetector

Mixed-dimensional heterostructures provide additional freedom to construct diverse functional electronic and optoelectronic devices, gaining significant interest. Herein, highly-aligned pseudo-1D tellurium is epitaxially grown on 2D monolayer transition metal dichalcogenides (TMDs), including MoSe₂, MoS₂, and WS₂. A one-pot chemical vapor deposition (CVD) technique eliminates the normally required transfer steps, thereby producing mixed-dimensional heterostructures with an ultraclean interface. The controllable epitaxial growth of Te/TMD heterostructures are verified by Raman, scanning probe microscopy (SPM), and transmission electron microscopy (TEM) observation. The photoluminescence results indicate that the emission from TMDs is quenched in the heterostructure, confirming the efficient transfer of photogenerated carriers from TMDs to Te. Additionally, the mixed-dimensional p-n Te/MoSe₂ heterojunction photodetector presents self-driven behavior with high responsivity (328 mA W⁻¹), external quantum efficiency (79%), and specific detectivity (8.2 × 10⁹ Jones). The modified facile synthesis strategy and proposed growth mechanism in this study shed light on synthesizing mixed-dimensional heterojunctions. This opens avenues for fabricating functional devices with reduced sizes and high densities, further enabling miniaturization and integration opportunities.     

Can a Large Number of Transplanted Mesenchymal Stem Cells Have an Optimal Therapeutic Effect on Improving Ovarian Function?

Mesenchymal stem cells (MSCs) are next-generation treatment in degenerative diseases. For the application of mesenchymal stem cell therapy to degenerative disease, transplantation conditions (e.g., optimized dose, delivery route and regenerating efficacy) should be considered. Recently, researchers have studied the mode of action of MSC in the treatment of ovarian degenerative disease. However, the evidence for the optimal number of cells for the developing stem cell therapeutics is insufficient. The objective of this study was to evaluate the efficacy in ovarian dysfunction, depends on cell dose. By intraovarian transplantation of low (1 × 10⁵) and high (5 × 10⁵) doses of placenta-derived mesenchymal stem cells (PD-MSCs) into thioacetamide (TAA)-injured rats, we compared the levels of apoptosis and oxidative stress that depend on different cell doses. Apoptosis and oxidative stress were significantly decreased in the transplanted (Tx) group compared to the non-transplanted (NTx) group in ovarian tissues from TAA-injured rats (* p < 0.05). In addition, we confirmed that follicular development was significantly increased in the Tx groups compared to the NTx group (* p < 0.05). However, there were no significant differences in the apoptosis, antioxidant or follicular development of injured ovarian tissues between the low and high doses PD-MSCs group. These findings provide new insights into the understanding and evidence obtained from clinical trials for stem cell therapy in reproductive systems.     

N-Functionalization of 5-Aminotetrazoles: Balancing Energetic Performance and Molecular Stability by Introducing ADNP

5-aminotetrazole is one of the most marked high-nitrogen tetrazole compounds. However, the structural modification of 5-aminotetrazole with nitro groups often leads to dramatically decreased molecular stability, while the N-bridging functionalization does not efficiently improve the density and performance. In this paper, we report on a straightforward approach for improving the density of 5-aminotetrazole by introducing 4-amino-3,5-dinitropyrazole. The following experimental and calculated properties show that nitropyrazole functionalization competes well with energetic performance and mechanic sensitivity. All compounds were thoroughly characterized using IR and NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Two energetic compounds (DMPT-1 and DMPT-2) were further confirmed by implementing single-crystal X-ray diffraction studies. Compound DMPT-1 featured a high crystal density of 1.806 g cm⁻³, excellent detonation velocity (v_D = 8610 m s⁻¹), detonation pressure (P = 30.2 GPa), and impact sensitivity of 30 J.