Effect of woven yarn angle on the low-velocity impact damage response of fibre woven thermoplastic composites

Fibre woven thermoplastic composites (FWTC) are widely used in aerospace and other fields because of their excellent performance. During service, FWTC structures are inevitably subjected to low-velocity impact (LVI), which can cause invisible damage and eventual failure of the material. At the moment, studies on FWTC mostly focused on the orthogonal woven yarns while there's few reports about the effect of the yarn angle changing on the woven material's LVI damage response. This study aims at the effect of yarn angle changing on the damage behaviour of FWTC. A method for preparation of nonorthogonal prepregs was proposed, by which FWTC laminates with different yarn angles (60°, 75°, and 90°) were prepared for LVI tests. The results show that the maximum impact displacement and the impact duration of the impactor decrease with the decrease of the yarn angle when the FWTC laminate is subjected to LVI, while the maximum impact force shows an increasing trend. This indicates that the smaller yarn angle causes the better load-bearing capacity of the FWTC laminate under LVI conditions, while the orthogonal FWTC laminate is more ductile. The damage morphology indicated by the impact of the FWTC laminate are matrix cracks and yarn breaks, and the damage area increases with the decrease of yarn angle, where the damage of orthogonal laminate is more serious more concentrated. The results found in this paper can provide useful guidance for engineering applications and failure analysis of FWTC.     

基于覆盖与故障注入的飞控软件测试技术研究

无人机飞控软件是典型的实时嵌入式软件系统,其可靠性、安全性测试与评估是军用软件保障工作与无人机技术发展中的重点与难点。针对飞控软件的特点,介绍基于覆盖与故障注入的测试方法．分析其测试与可靠性评估中的关键技术,并简要介绍应用于测试数据分析过程的软件可靠性建模工具MEADEP的构成与建模方法。实践证明对安全关键软件严格的测试与评估可大大降低错误隐藏数,减少不必要的经济损失与灾难性事件发生。     

The Pt(S-pr-thiosal)2 and BCL1 Leukemia Lymphoma: Antitumor Activity In Vitro and In Vivo

B cell malignancies are, despite the development of targeted therapy in a certain percentage of the patients still a chronic disease with relapses, requiring multiple lines of therapy. Regimens that include platinum-based drugs provide high response rates in different B cell lymphomas, high-risk chronic lymphocytic leukemia (CLL), and devastating complication of CLL, Richter’s syndrome. The aim of this study was to explore the potential antitumor activity of previously synthetized platinum(IV) complex with alkyl derivatives of thyosalicilc acid, PtCl2(S-pr-thiosal)2, toward murine BCL1 cells and to delineate possible mechanisms of action. The PtCl2(S-pr-thiosal)2 reduced the viability of BCL1 cells in vitro but also reduced the growth of metastases in the leukemia lymphoma model in BALB/c mice. PtCl2(S-pr-thiosal)2 induced apoptosis, inhibited proliferation of BCL1 cells, and induced cell cycle disturbance. Treatment of BCL1 cells with PtCl2(S-pr-thiosal)2 inhibited expression of cyclin D3 and cyclin E and enhanced expression of cyclin-dependent kinase inhibitors p16, p21, and p27 resulting in cell cycle arrest in the G1 phase, reduced the percentage of BCL1 cells in the S phase, and decreased expression of Ki-67. PtCl2(S-pr-thiosal)2 treatment reduced expression of phosphorylated STAT3 and downstream-regulated molecules associated with cancer stemness and proliferation, NANOG, cyclin D3, and c-Myc, and expression of phosphorylated NFκB in vitro and in vivo. In conclusion, PtCl2(S-pr-thiosal)2 reduces STAT3 and NFκB phosphorylation resulting in inhibition of BCL1 cell proliferation and the triggering of apoptotic cell death.     

军队装备维修工程CBM综述

军队维修体制从传统的定期维修、预防性维修向以可靠性维修（reliability centered maintenance,RCM）为指导的状态维修（condition based maintenance,CBM）和设备健康状态管理（equipment health management,EHM）方式过渡,是军队维修工程信息化、智能化管理进程中的必经之路。介绍了状态维修的基本概念及层次结构,对其国内外应用现状及主要应用价值进行了分析,阐述了CBM在我军维修工程中的实施对策及对三级维修体制的影响。     

Analysis of Mg content of Zn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Mg<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O film grown on sapphire substrates by plasma-assisted molecular beam epitaxy

The Mg content of Zn_1−x Mg _x O film grown on A-sapphire substrates by plasma-assisted molecular beam epitaxy is measured by inductively coupled plasma (ICP) and electronic probe microanalysis (EPMA). A theoretical model for analyzing the difference in the Mg content between Zn-rich and Zn-deficient conditions in the growth process is established, and the mathematical relation between Mg content and the temperature of the Mg cell is formulated under Zn-rich condition. The formula derived is proven to be correct by experiments.     

Non-uniform mixing of hepatic venous flow and inferior vena cava flow in the Fontan conduit

Fontan patients require a balanced hepatic blood flow distribution (HFD) to prevent pulmonary arteriovenous malformations. Currently, HFD is quantified by tracking Fontan conduit flow, assuming hepatic venous (HV) flow to be uniformly distributed within the Fontan conduit. However, this assumption may be unvalid leading to inaccuracies in HFD quantification with potential clinical impact. The aim of this study was to (i) assess the mixing of HV flow and inferior vena caval (IVC) flow within the Fontan conduit and (ii) quantify HFD by directly tracking HV flow and quantitatively comparing results with the conventional approach. Patient-specific, time-resolved computational fluid dynamic models of 15 total cavopulmonary connections were generated, including the HV and subhepatic IVC. Mixing of HV and IVC flow, on a scale between 0 (no mixing) and 1 (perfect mixing), was assessed at the caudal and cranial Fontan conduit. HFD was quantified by tracking particles from the caudal (HFD_{caudal conduit}) and cranial (HFD_{cranial conduit}) conduit and from the hepatic veins (HFD_HV). HV flow was non-uniformly distributed at both the caudal (mean mixing 0.66 ± 0.13) and cranial (mean 0.79 ± 0.11) level within the Fontan conduit. On a cohort level, differences in HFD between methods were significant but small; HFD_HV (51.0 ± 20.6%) versus HFD_{caudal conduit} (48.2 ± 21.9%, p = 0.033) or HFD_{cranial conduit} (48.0 ± 21.9%, p = 0.044). However, individual absolute differences of 8.2–14.9% in HFD were observed in 4/15 patients. HV flow is non-uniformly distributed within the Fontan conduit. Substantial individual inaccuracies in HFD quantification were observed in a subset of patients with potential clinical impact.     

Parametric analysis and yearly performance of a trigeneration system driven by solar‐dish collectors

Solar‐driven polygeneration systems are promising technologies for covering many energy demands with a renewable and sustainable way. The objective of the present work is the investigation of a trigeneration system, which is driven by solar‐dish collectors. The examined trigeneration system includes an organic Rankine cycle (ORC), which operates with toluene, and an absorption heat pump, which operates with LiBr/H₂O. The absorption heat pump is fed with heat by the condenser of the ORC, which operates at medium temperature levels (120°C to 150°C). The absorption heat pump produces both useful heat at 55°C and cooling at 12°C. The ORC produces electricity, and it is fed by the solar dishes. The examined ORC is a regenerative cycle with superheating. The total analysis is performed with a developed model in Engineering Equation Solver (EES). The system is investigated parametrically for different ORC heat‐rejection temperatures, different superheating levels in the turbine inlet, and various solar‐beam irradiation levels. Furthermore, the system is investigated on a yearly basis for the climate conditions of Athens (Greece) and for Belgrade (Serbia). It is found that the yearly system energy and exergy efficiencies are 108.39% and 20.92%, respectively, for Athens, while 111.38% and 21.50%, respectively, for Belgrade. The values over 100% for the energy efficiency are explained by the existence of a heat pump in the examined configuration. For both locations, the payback period is found close to 10 years and the internal rate of return close to 10%. The final results indicate that the examined configuration is a highly efficient and viable system, which operates only with a renewable energy source.     

Single-Shot Fabrication of Semiconducting–Superconducting Nanowire Devices

Semiconducting–superconducting hybrids are vital components for the realization of high-performance nanoscale devices. In particular, semiconducting–superconducting nanowires attract widespread interest owing to the possible presence of non-abelian Majorana zero modes, which are quasiparticles that hold promise for topological quantum computing. However, systematic search for Majoranas signatures is challenging because it requires reproducible hybrid devices and reliable fabrication methods. This work introduces a fabrication concept based on shadow walls that enables the in situ, selective, and consecutive depositions of superconductors and normal metals to form normal-superconducting junctions. Crucially, this method allows to realize devices in a single shot, eliminating fabrication steps after the synthesis of the fragile semiconductor/superconductor interface. At the atomic level, all investigated devices reveal a sharp and defect-free semiconducting–superconducting interface and, correspondingly, a hard induced superconducting gap resilient up to 2 T is measured electrically. While the cleanliness of the technique enables systematic studies of topological superconductivity in nanowires, it also allows for the synthesis of advanced nano-devices based on a wide range of material combinations and geometries while maintaining an exceptionally high interface quality.     

巨型框架结构体系抗震研究综述

综述巨型框架结构体系在国内外的工程应用情况,以及该结构体系抗震性能理论分析方法和试验方法,指出巨型框架结构体系抗震研究的方向。