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221.
高校图书流通的5M1E管理法   总被引:1,自引:1,他引:0  
借鉴质量管理中的"人机料法环测"(5M1E)因果分析管理方法,提出了高校图书流通管理的5M1E分析管理方法.在分析高校图书流通过程中诸要素的作用及其相互关系的基础上,阐述了"以读者为核心,以网络为平台,以图书为对象,依规程做约束.依测量做评价,依环境做创新"的高校图书流通管理指导思想及分析管理方法.  相似文献   
222.
Three-dimensional(3D) braided composites are a kind of advanced ones and are used in the aeronautical and astronautical fields more widely. The advantages, usages, shortages and disadvantages of 3D braided composites are analyzed, and the possible approach of improving the properties of the materials is presented, that is, a new type of 3D full 5-directional braided composites is developed. The methods of making this type of preform are proposed. It is pointed out that the four-step braiding which is the most possible to realize industrialized production almost has no effect on the composites'properties. By analyzing the simulation model, the advantages of the material compared with the 3D 4-di- rectional and 5-directional materials are presented. Finally, a microstructural model is analyzed to lay the foundation for the future theoretical analysis of these composites.  相似文献   
223.
GTO objects can potentially collide with operative satellites in LEO and GEO protected regions. Internationally accepted debris mitigation guidelines require that these objects exit these protected regions within 25?years, e.g. by re-entering and burning up in Earth’s atmosphere. In this paper, an inventory of the GTO debris generated from Ariane 5 launches in the period 2012–2017 is provided, and it is expected that none of these objects will re-enter within 25?years. For future launches, natural perturbations can be exploited to increase compliance with mitigation guidelines without the use of extra propellant or complex de-orbiting systems, which is attractive from an economic point of view. The lifetime of GTO objects is very sensitive to initial conditions and some environmental and body-related parameters, mainly due to the effect of solar gravity on the perigee altitude. As a consequence, the lifetime of a specific GTO object cannot be predicted accurately, but its probability of re-entering in less than 25?years can be estimated with proper accuracy by following a statistical approach. By propagating the orbits of over 800,000 simulated Ariane 5 GTO objects, it was found that the launch time leading to the highest probability of compliance with debris mitigation guidelines for GEO launches from Kourou corresponds to about 2 PM local time, regardless of the date of launch, which leads to compliance rates ranging from 60 to 100%. Current practice is to launch at around 5–9?PM, so a change in procedures would be required in order to reach a higher degree of compliance with debris mitigation guidelines, which was predicted to be on average below 20% for the objects generated in the period 2012–2017.  相似文献   
224.
New meteor radar (MR) horizontal wind data obtained during 2015–2018 at Kazan (56°N, 49°E) are presented. The measurements were carried out with a state-of-the-art SKiYMET meteor radar. Monthly mean vertical profiles of zonal and meridional components of the prevailing wind speeds, also amplitudes and phases of the components of diurnal (DT) and semidiurnal tide (SDT) winds are displayed as contour plots for a mean calendar year over the four recent years and compared with distributions of these parameters provided by the previous multiyear (1986–2002) meteor radar (MR) measurements at Kazan and by the recent HWM07 empirical model. The analysis shows that the SKiYMET zonal and meridional prevailing wind speeds are generally in good agreement, sharing the same seasonal features, with the earlier MR seasonal winds. Comparisons with the HWM07 model are not favourable: eastward solstitial cells as modelled are significantly larger, >30?m/s compared to 15–20?m/s. Also, reversal lines are too variable with height, and the positions of modelled cells (positive and negative) are unlike those of either MRs at Kazan or other MLT radars. Both MR systems provide the large SDT amplitudes, approximately 30?m/s and vertical wavelengths, approximately 55?km, for both components at middle latitudes in winter. They also show the well known strong SDT September feature (heights 85–100?km, the vertical wavelength ~55–60?km), and the weak summer SDT for 80–91?km. HWM07 shows unrealistic amplitudes and phases above 90?km by height and month: minimal amplitudes in equinoxes and no September feature.The weak DT of middle to high latitudes provide similar amplitude and phase structures from both MRs, 1986–2002 and 2015–2017: largest amplitudes (10–12 or 8–10?m/s) for the evanescent meridional tide in summer, peaking in late July; weakest (0–2, 2–4?m/s) at 80 to 92–96?km, when the tide is vertically propagating (January, February, November, December) with a vertical wavelength near 40?km. Again, HWM07 differs in amplitude and phase structures: showing peak amplitudes in equinoxes: April, 15?m/s at 88?km; October, 21?m/s at 89?km.Coupling of the MR wind parameters with the ERA5 wind parameters is studied for a case in 2016. It is shown that the prevailing winds and DT amplitudes and phases of both datasets can be simply linked together, but that the ERA5 SDT amplitudes are significantly underestimated at the top model levels of the ERA5 reanalysis project.  相似文献   
225.
本文介绍了水杨醛缩-5-碘-8-氨基喹啉新西夫碱的合成、提纯与鉴定。特别对其性质及其与镓金属离子显色反应的光度特性作了研究,其配合物3.49×104L·mol(-1)·cm(-1).  相似文献   
226.
利用激光熔化沉积技术制备15-5PH沉淀硬化不锈钢板,利用金相显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、电子探针(EPMA)技术,对沉积态组织进行分析,测试沉积态组织的室温拉伸性能。结果表明:激光熔化沉积15-5PH不锈钢沉积态组织由沿沉积增高方向贯穿多层外延生长的柱状晶组成,柱状晶内包含多个细长整齐排列的胞状树枝晶,枝晶内为马氏体组织,枝晶间为铁素体;沉积态组织中弥散分布大量细小的NbC析出相,尺寸12~20 nm;15-5PH不锈钢沉积态组织具有良好的力学性能,纵向抗拉强度和延伸率分别为1 128.5 MPa和14.0%,横向抗拉强度和延伸率分别为1 101 MPa和12.25%。  相似文献   
227.
Precipitation is an important component of the hydrological and energy cycles, as well as a key input parameter for many applications in the fields of hydrology, climatology, meteorology, and weather forecasting research. As a result, estimating precipitation accurately is critical. The purpose of this research is to conduct a comprehensive and comparative evaluation of grid-based precipitation products over Turkey's Mediterranean region from 2017 to 2021 at monthly and grid scales, using data from 193 ground-based meteorological stations as a reference. PERCIANN CCS, PDIR-Now, GSMaP MVK, PERSIANN CDR, CHIRPS, IMERG v6, GSMaP Gauge, and ERA5 are the eight grid-based precipitation products. Several prospective were used to evaluate the products, including magnitude agreement with gauge stations for the entire region and the six hydrological sub-basins included in the region, performance in capturing various intensity categories, and elevation dependency. According to the evaluation results, PERCIANN CDR, CHIRPS, IMERG v6, GSMaP Gauge, and ERA5 performed well in all evaluation aspects, whereas PERCIANN CCS, PDIR-Now, and GSMaP MVK performed poorly in all metrics. The majority of the products underestimated heavy rainfall events, while all products performed better at low and moderate precipitation events. As a result, the products performed better in the summer and spring months (March to October) than in the winter months (December to February). Furthermore, the results showed that the performance of the majority of the products degraded for elevations greater than 1000 m. The evaluation suggests that PERSIANN CDR, CHIRPS, IMERG v6, GSMaP Gauge, and ERA5 can be used as good precipitation data sources and as a complement to ground-based meteorological stations in Turkey's Mediterranean region.  相似文献   
228.
三维五向碳/酚醛编织复合材料的拉伸性能及破坏机理   总被引:7,自引:0,他引:7  
 对不同编织角、不同体积含量的三维五向碳/酚醛编织复合材料进行了纵向(编织方向)拉伸实验和横向拉伸的对比实验,获得了这些编织复合材料的主要拉伸力学性能。实验后对拉伸试件的断口进行了照相和扫描电镜观察,分析了材料的变形及其破坏机理。实验结果表明: 编织角仍是影响三维五向编织复合材料拉伸力学性能的主要因素,并且复合工艺的质量对复合材料的力学性能有重要影响。此外,发现三维五向碳/酚醛编织复合材料的横向拉伸与纵向拉伸具有完全不同的破坏机制。  相似文献   
229.
In this work, the Nb–14Si–24Ti–10Cr–2Al–2Hf–0.1Y alloy(at.%) was processed by the liquid–metal-cooled directional solidification(DS) at 1750 C with withdrawal rates of 1.2, 6,18 mm/min and post heat treatment(HT) at 1450 C for 10 h. The microstructures of the directionally solidified and heat treated samples were investigated. The results show that the microstructure of directionally solidified alloy mainly consists of petaloid Nbss+ Nb5Si3eutectics and Ti-rich Nbss+ Nb5Si3+ Cr2Nb eutectics. With the increase of withdrawal rate, the primary Nb5Si3is eliminated, Nbss+ Nb5Si3eutectic cells turn round and connected with the microstructure refinement and Nbss+ Nb5Si3+ Cr2Nb eutectics turn to a river-like morphology. After heat treatment,Nbss+ Nb5Si3+ Cr2Nb eutectics disappeared and petaloid Nbss+ Nb5Si3eutectics turn to a specific fiber-mesh structure gradually, which is promoted by higher withdrawal rates. Furthermore,both the volume fraction of Cr2Nb and the content of Cr in Nbssof Nbss+ Nb5Si3eutectics change regularly with the increase of withdrawal rate and heat treatment at 1450 C for 10 h.  相似文献   
230.
根据PTB和ISO 4037-1:2019要求,关于高空气比释动能系列(H系列)X射线参考辐射质的推荐数据,外推得出H-450的附加过滤为6.24 mm Cu,第一半值层(HVL1st)为(5.39~5.52)mm Cu,平均光子能量为(214.25~214.78)keV,剂量率为11.51 Gy/h(距离焦斑为1 m处,管电流为10 mA)。随后,使用PTW32005电离室作为测量器具,采用半值层法建立H-450 X射线参考辐射质,得出HVL1st5.37 mm Cu,第二半值层(HVL2nd)为5.97 mm Cu,同质系数为0.9。最后,使用PTW30013次级标准电离室测量得出H-450 X射线参考辐射质下距离焦斑1 m,管电流为10 mA时的剂量率值为11.98 Gy/h,与理论值的相对误差为4.07 %。采用MCNP 5软件对H-450 X射线参考辐射质进行能谱模拟并计算得出其平均光子能量为200.4 keV。  相似文献   
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