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61.
《语用学新解》明确了语用在语言研究中的地位,阐述了语言的产生和理解无不是变异、协商和顺应等语用因素相互作用的结果。作者认为它可以用以拓宽翻译理论和方法的研究,并为翻译学科的新发展提供系统的理论基础。  相似文献   
62.
In this paper, data of (B0, B1) parameters deduced from the electron density profiles that are inverted from the ionograms recorded at Hainan (19.4°N, 109.0°E), China during a three year period from March 2002 to February 2005 are used to study the diurnal and seasonal variation of (B0, B1) parameters at low latitude. The observational results are compared with the IRI2001 model predictions. Variability study of (B0, B1) in terms of percentage ratio of the inter-quartiles to the median values and correlative analysis between (B0, B1) parameters and other ionospheric characteristics such as hmF2 and M(3000)F2 are also made. Our present study showed that: (1) for daytime hours, the IRI2001 model results with new table option (B0_Tab) is in a better agreement with the observational results (B0_Obs) than the IRI2001 model results with Gulyaeva option (B0_Gul) for summer season, whereas B0_Gul is in a better agreement with B0_Obs than B0_Tab for winter season. For nighttime, in general, B0_Gul is in a better agreement with B0_Obs than B0_Tab. For other occasions, both B0_Tab and B0_Gul showed some systematic deviations from the observational ones. Moreover, the deviations of B0_Tab and B0_Gul from B0_Obs showed opposite trends; (2) the monthly upper (lower) quartiles of (B0, B1) parameter showed a good linear relationship with the monthly median values, this makes it possible to do the regression analysis between the monthly upper (lower) quartiles and the monthly median values, which can give a measure of the variability of these parameters. In terms of the percentage ratio of the inter-quartiles to the median values, the variability of B0 showed a diurnal variation ranging between 22% and 36% with maximum value occurring at pre-sunrise hours, whereas the variability of B1 showed a diurnal variation ranging between 15% and 30% with higher value by daytime than at night; (3) B0 shows high linear correlative relationships with hmF2 and M(3000)F2 for most of the local time period of a day except for a few hours around midnight, whereas B1 showed high linear correlations with B0, hmF2 for daytime hours, but not for nighttime hours. This suggests that it maybe is possible to obtain the synthetic database of (B0, B1) parameter or to construct the model of (B0, B1) using database of hmF2 or M(3000)F2 which is much easier to obtain from experimental measurements.  相似文献   
63.
In this paper, latitudinal profiles of the vertical total electron content (TEC) deduced from the dual-frequency GPS measurements obtained at ground stations around 120°E longitude were used to study the variability of the equatorial ionization anomaly (EIA). The present study mainly focuses on the analysis of the crest-to-trough TEC ratio (TEC-CTR) which is an important parameter representing the strength of EIA. Data used for the present study covered the time period from 01 January, 1998 to 31 December, 2004. An empirical orthogonal function analysis method is used to obtain the main features of the TEC-CTR’s diurnal and seasonal variations as well as its solar activity level dependency. Our results showed that: (1) The diurnal variation pattern of the TEC-CTR at 120°E longitude is characterized by two remarkable peaks, one occurring in the post-noon hours around 13–14 LT, and the other occurring in the post-sunset hours around 20–21 LT, and the post-sunset peak has a much higher value than the post-noon one. (2) Both for the north and south crests, the TEC-CTR at 120°E longitude showed a semi-annual variation with maximum peak values occurring in the equinoctial months. (3) TEC-CTR for the north crest has lower values in summer than in winter, whereas TEC-CTR for the south crest does not show this ‘winter anomaly’ effect. In other words, TEC-CTR for both the north and south crests has higher values in the northern hemispheric winter than in the northern hemispheric summer. (4) TEC-CTR in the daytime post-noon hours (12–14 LT) does not vary much with the solar activity, however, TEC-CTR in the post-sunset hours (19–21 LT) shows a clear dependence on the solar activity, its values increasing with solar activity.  相似文献   
64.
Since November 1978 a complete set of total solar irradiance (TSI) measurements from space is available, yielding a time series of 21 years. From measurements made by different space radiometers (HF on NIMBUS-7, ACRIM I on SMM, ACRIM II on UARS and VIRGO on SOHO) a composite record of TSI can be compiled. The corrections which are needed for each radiometer, mainly to compensate for degradation, but also for operational influences are described. ACRIM I (1980–1989) and ACRIM II (1992–1995) are taken as reference because their degradation was monitored by inflight comparisons with spare radiometers; since 1996 VIRGO is used as reference. The scale of ACRIM II is adjusted to ACRIM I by comparison with NIMBUS-7 and ERBE. The reliability of this adjustment depends strongly on the stability of the HF and ERBE radiometer during the period of the gap between the ACRIMs which is discussed in detail together with an assessment of the overall precision of the composite.  相似文献   
65.
为研究心率变异性(HRV)指标在管制员(ATC)疲劳检测中的适用性,搭建模拟管制实验平台,利用生理记录仪实时记录20名被试正常和疲劳状态下的心电(ECG)信号,并采集其主观疲劳度(卡罗林斯卡嗜睡量表)和操作绩效。利用偏相关分析选取与被试疲劳等级相关性高的心率变异性指标,并用于管制员疲劳检测的多元线性回归建模。分析结果表明:SDNN与被试的疲劳状态无相关性;LFnorm和HFnorm与疲劳程度呈弱相关;RR间期均值、LF/HF均与被试的疲劳度存在较强的相关性,二者结合建立的多元线性回归模型,拟合优度大于0.5,RR间期均值和LF/HF可作为检测管制员疲劳的有效指标。本文研究成果可为未来的管制员疲劳实时检测提供科学依据和实验支撑。   相似文献   
66.
Observations of the chromosphere with Deslandres’s spectroheliograph started at Paris Observatory in 1893 and were followed by systematic observations at Meudon since 1908. The solar collection of Hα and CaII K images is probably the longest available worldwide, with associated products such as synoptic maps and tables. Since 2018, Meudon spectroheliograph is the only instrument producing data-cubes of full line profiles of CaII H, CaII K and Hα, for each pixel of the solar disk. Slices of the cubes provide monochromatic images. We summarize in this paper the capabilities of the successive generations of the instrument, and explore the potential of the collection and products for analysis of rare events, investigations of past solar activity and studies of long term variability.  相似文献   
67.
对星载电扫合成孔径雷达斜视滑动聚束模式,采用传统波束扫描策略中出现的方位向分辨率沿方位向空变大及方位扫描角度过大的问题展开研究。首先,分析采用传统斜视滑动聚束扫描策略情况下,方位向分辨率沿方位向出现空变的原因,探究方位向分辨率与扫描策略、扫描角度的关系。然后,提出基于全局搜索增强鲸鱼优化算法的斜视滑动聚束波束扫描策略,控制不同时刻下的方位向扫描角速度,降低方位向分辨率沿方位向的空变程度,减小天线最大方位向扫描角度,缩短数据录取时间,有效降低系统代价,提升系统性能。最后,通过仿真验证所提策略的有效性,方位向分辨率空变降低至1%以下,数据录取时间与总扫描角度相较于原有方法降低10%以上。  相似文献   
68.
The paper presents an analysis of the ionospheric variability as a function of local time, month, and geomagnetic activity level. The 2003–2020 dataset of peak electron densities (NmF2) from the Irkutsk DPS-4 Digisonde (52.3°N, 104.3°E) was converted into the dataset of the NmF2 disturbances (ΔNmF2) representing the relative (percentage) deviations of the NmF2 from the 27-day running median. The ΔNmF2 dataset was used to calculate root mean square values of ΔNmF2 (σNmF2) by 27-day running averaging. These σNmF2 values were considered as a measure of ionospheric variability. The σNmF2 as function of local time, day of year, and year was the input for building the local empirical model of ionospheric variability based on the linear regression of σNmF2 on the 27-day average daily Ap-index of geomagnetic activity. The paper demonstrates the diurnal-seasonal variations in σNmF2 under low geomagnetic activity (linear regression intercept) as well as the rate of increase/decrease in σNmF2 with increasing Ap (linear regression slope). The obtained diurnal, seasonal, and geomagnetic activity behavior of σNmF2 is compared with previous studies of ionospheric variability.  相似文献   
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