The Age-Redshift Relationship of Old Passive Galaxies

We use 32 age measurements of passively evolving galaxies as a function of redshift to test and compare the standard model ($\Lambda$CDM) with the $R_{\rm h}=ct$ Universe. We show that the latter fits the data with a reduced $\chi^2_{\rm dof}=0.435$ for a Hubble constant $H_{0}= 67.2_{-4.0}^{+4.5}$ km $\rm s^{-1}$ $\rm Mpc^{-1}$. By comparison, the optimal flat $\Lambda$CDM model, with two free parameters (including $\Omega_{\rm m}=0.12_{-0.11}^{+0.54}$ and $H_{0}=94.3_{-35.8}^{+32.7}$ km $\rm s^{-1}$ $\rm Mpc^{-1}$), fits the age-\emph{z} data with a reduced $\chi^2_{\rm dof}=0.428$. Based solely on their $\chi^2_{\rm dof}$ values, both models appear to account for the data very well, though the optimized $\Lambda$CDM parameters are only marginally consistent with those of the concordance model ($\Omega_{\rm m}=0.27$ and $H_{0}= 70$ km $\rm s^{-1}$ $\rm Mpc^{-1}$). Fitting the age-$z$ data with the latter results in a reduced $\chi^2_{\rm dof}=0.523$. However, because of the different number of free parameters in these models, selection tools, such as the Akaike, Kullback and Bayes Information Criteria, favour $R_{\rm h}=ct$ over $\Lambda$CDM with a likelihood of $\sim 66.5\%-80.5\%$ versus $\sim 19.5\%-33.5\%$. These results are suggestive, though not yet compelling, given the current limited galaxy age-$z$ sample. We carry out Monte Carlo simulations based on these current age measurements to estimate how large the sample would have to be in order to rule out either model at a $\sim 99.7\%$ confidence level. We find that if the real cosmology is $\Lambda$CDM, a sample of $\sim 45$ galaxy ages would be sufficient to rule out $R_{\rm h}=ct$ at this level of accuracy, while $\sim 350$ galaxy ages would be required to rule out $\Lambda$CDM if the real Universe were instead $R_{\rm h}=ct$.Comment: 36 pages, 13 figures, 1 table; accepted for publication in The Astronomical Journal. arXiv admin note: text overlap with arXiv:1405.238

An experimental and numerical study on structural dynamic stress of a landing gear

This paper concerns the main landing gear of certain light aircraft, and the dynamic stress on the main landing gear during the landing process is analyzed. A complete dynamic drop test is developed for the landing gear of light aircraft on the main landing gear, and the changes of dynamic strain exerted on the strut in the process of drop are measured. Simultaneously, the simulation software LMS Virtual.Lab Motion is used to build the rigid-flexible coupling dynamic model and simulate the process of drop and the results of the dynamic stress is obtained by means of computer simulation. Afterwards, the results of the dynamic stress between simulation and test are contrasted, and the sources of data error are analyzed. To sum up, the study shows that the dynamic stress in the flexible part of landing gear possesses a high accuracy through combining the analysis results of simulation and test, which meets the safety design criteria of the landing gear. Moreover, the method used to build the rigid-flexible coupling model is an available and reliable way for the simulation of drop test, which can provide a deep basis for future research

The Relationship Between Political Skill And Employee Voice Behavior From An Impression Management Perspective

This research focused on the self-serving motivation of voice behavior from an impression management perspective, different from the previous studies on the altruistic motivation. The purpose of this study was to construct a multilevel theoretical model that proposed how political skill operates to exercise effects on employee voice behavior in the context of organizational politics climate from an impression management perspective. We hypothesized the positive relationship between political skill and employee voice behavior, and the mediating role of impression-management motives, and then examined the cross-level effects of organizational politics climate on the individual-level employee voice phenomenon. An evaluation of research limitations, suggestions for future research, contributions to the literature and practical implications were discussed finally

Analysis of Vegetation Coverage Dynamics of YongDeng County Using Normalized Difference Vegetation Index (NDVI) and Pixel Binary Model

The research is supported by the fundamental research funds of Gansu provincial natural science fund of “Research on Land use and Ecological Security in Ecologically Vulnerable Areas” (project No. GSAN-ZL-2015-045) and “Research on the Coordination Relationship between Land Urbanization and Population Urbanization” (project No. GSAU-ZL-2015-046) Abstract Under the current background of global climate change, it is very important to study the temporal and spatial characteristics of vegetation cover which will provide a scientific basis for ecosystem management decisions that will protect the integrity of biodiversity and ensure a continuous supply of valuable ecological services. The objective of this study was to use the normalized difference vegetation index and the pixel binary model in ENVI to analyze the vegetation cover dynamics of YongDeng County using 1993, 2001, 2009, and 2017 satellite images. Satellite images were obtained from the Geospatial Data Cloud (Http/westdc.westgis.ac.cn). Combined with the vegetation coverage information and unique ecological characteristics of the study area, the vegetation coverage types were classified into four grades as Grade I (Bare land, water, and built-up environment), grade II (Low yield grassland and sparse vegetation classified), grade III (Middle grassland and vegetation of cultivated land) and grade IV (Dense woodland and shrubs). The results showed a dynamic trend in the different grades of vegetation cover in the study area from 1993 to 2017. Grade I vegetation-covered an area of 1208.72 km² and 1098.09 km² in 1993 and 2001 respectively but decreased to 375.99 km² in 2009 and finally increased slightly to 398.88 km² in 2017. Grade II vegetation cover did not show significant changes over the years considered for this study. It covered an area of 3821.2 km² and 3803.1 km² in 1993 and 2001 respectively. In 2009 and 2017 it covered approximately 3769.2 km² and 3787.82 km² respectively. Grade III vegetation cover showed an increasing trend from 1993 to 2017. From 334.76 km² in 1993, it increased to 468.28 km² and 980.39 km² in 2001 and 2009 respectively, and finally increased further to 1008.5 km² in 2017. Grade IV vegetation-covered an area of 4552.62 km², 442.6 km², and 667.52 km² in 1993, 2001, and 2009 respectively and finally reduced slightly to 596.64 km² in 2017. Economic development in areas such as mining, construction, and urbanization played a major role in reducing Grade I vegetation cover. Grade II did not show any significant change because of fewer disturbances as a result of their inaccessible nature to humans. Expansion and Continues farming throughout the year as a result of the presence of an irrigation system in the area accounted for the increasing trend of Grade III vegetation cover. This study reveals there is an urgent need for measures to be put in place to mitigate activities that lead to the removal of vegetation cover as this may have serious implications on the supply of important ecological services. Keywords: Vegetation coverage, YongDeng, NDVI, Pixel Binary model, dynamic analysis DOI: 10.7176/JEES/10-9-09 Publication date:September 30th 202