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分析煤样烘干时间与空干时间的关系研究 被引量:2
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作者 张辉 赖志彬 +1 位作者 阮勇防 吴广智 《煤质技术》 2012年第1期32-34,共3页
通过分析煤样在不同烘干时间下对空干时间的影响,得出分析煤样烘干时间与空干时间的关系,从而优选出煤样的最佳烘干时间。
关键词 分析煤样 制样 时间 空干时间
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Space-time spreading and space-time coding for correlated frequency-selective channel in the presence of interference 被引量:2
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作者 肖海林 Nie Zaiping Li Xin 《High Technology Letters》 EI CAS 2008年第1期81-84,共4页
The space-time spreading (SIS), superimposed training sequences and space-time coding (STC) are adopted to obtain a closed-form of average error probability upper bound and maximum likelihood esti- mation expressi... The space-time spreading (SIS), superimposed training sequences and space-time coding (STC) are adopted to obtain a closed-form of average error probability upper bound and maximum likelihood esti- mation expression for multiple input and multiple output (MIMO) correlated frequency-selective channel in the presence of interference (colored interference). Moreover, the correlation at both ends of the wire- less link that can be incorporated equivalently into correlation at the transmit end is derived. Finally, the mean square error (MSE) of the maximum likelihood estimate is also derived. 展开更多
关键词 average error probability upper bound Chemoff bound maximum likelihood estimation space-time spreading (SIS) space-time coding (STC) mean square error
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Drought and Spatiotemporal Variability of Forest Fires Across Mexico 被引量:3
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作者 Pompa-García MARíN Camarero J.JULIO +1 位作者 Rodríguez-Trejo DANTE ARTURO Vega-Nieva DANIEL JOSE 《Chinese Geographical Science》 SCIE CSCD 2018年第1期25-37,共13页
Understanding the spatiotemporal links between drought and forest fire occurrence is crucial for improving decision-making in fire management under current and future climatic conditions. We quantified forest fire act... Understanding the spatiotemporal links between drought and forest fire occurrence is crucial for improving decision-making in fire management under current and future climatic conditions. We quantified forest fire activity in Mexico using georeferenced fire records for the period of 2005–2015 and examined its spatial and temporal relationships with a multiscalar drought index, the Standardized Precipitation-Evapotranspiration Index(SPEI). A total of 47975 fire counts were recorded in the 11-year long study period, with the peak in fire frequency occurring in 2011. We identified four fire clusters, i.e., regions where there is a high density of fire records in Mexico using the Getis-Ord G spatial statistic. Then, we examined fire frequency data in the clustered regions and assessed how fire activity related to the SPEI for the entire study period and also for the year 2011. Associations between the SPEI and fire frequency varied across Mexico and fire-SPEI relationships also varied across the months of major fire occurrence and related SPEI temporal scales. In particular, in the two fire clusters located in northern Mexico(Chihuahua, northern Baja California), drier conditions over the previous 5 months triggered fire occurrence. In contrast, we did not observe a significant relationship between drought severity and fire frequency in the central Mexico cluster, which exhibited the highest fire frequency. We also found moderate fire-drought associations in the cluster situated in the tropical southern Chiapas where agriculture activities are the main causes of forest fire occurrence. These results are useful for improving our understanding of the spatiotemporal patterns of fire occurrence as related to drought severity in megadiverse countries hosting many forest types as Mexico. 展开更多
关键词 cluster DROUGHT forest fires GEOSTATISTICS spatial clusters Standardised Precipitation-Evapotranspiration Index (SPEI)
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Experimental Investigation on Simultaneous Dry Blanching and Drying of Mushroom Slices Using Microwave Enhanced Hot Air Heating System 被引量:1
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作者 Ipsita Das Girish Kumar 《Journal of Food Science and Engineering》 2013年第10期517-524,共8页
The study evaluated the feasibility of using microwave enhanced hot air heating system for simultaneous dry blanching and dehydration of mushroom slices. The technology involves application of microwave energy at the ... The study evaluated the feasibility of using microwave enhanced hot air heating system for simultaneous dry blanching and dehydration of mushroom slices. The technology involves application of microwave energy at the beginning of dehydration process to inactivate enzymes as well as to remove a certain amount of moisture at the same time and then followed by hot air drying to complete the process. The study investigated effects of different processing parameters, i.e., microwave power level and exposure time on dehydration and quality characteristics of mushroom slices. Mushroom slices were pretreated with different microwave power levels of 240, 360 and 480 W for 1, 3 and 5 min before the hot air-drying. The optimum range of the microwave power level and pretreatment time was found to be 360 W, 3 min and 360 W, 1 min in obtaining the maximum and minimum levels of response parameters. 展开更多
关键词 DEHYDRATION dry blanching MICROWAVE mushroom slices.
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Linearly constrained SOLMS for adaptive space-time interference cancellation in STBC MIMO systems
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作者 单红梅 胡光锐 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2008年第2期176-178,共3页
This paper presents an adaptive linearly constrained second-order least mean-square (LC-SOLMS) algorithm for interference cancellation in space-time block coded MIMO systems with fading channels. By taking mean-output... This paper presents an adaptive linearly constrained second-order least mean-square (LC-SOLMS) algorithm for interference cancellation in space-time block coded MIMO systems with fading channels. By taking mean-output-energy (MOE) optimization method, an adaptive linear detection algorithm was built up, which can suppress multiple access interference and noise. Simulation results illustrate that the proposed algorithm has great interference cancellation capability and faster convergence performance. 展开更多
关键词 soace-time block code MIMO adaotive interference cancellation MOE
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Spatio-temporal Variation of Soil Respiration and Its Driving Factors in Semi-arid Regions of North China 被引量:3
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作者 ZENG Xinhua SONG Yigang +1 位作者 ZHANG Wanjun HE Shengbing 《Chinese Geographical Science》 SCIE CSCD 2018年第1期12-24,共13页
Soil respiration (SR) is the second-largest flux in ecosystem carbon cycling. Due to the large spatio-temporal variability of environmental factors, SR varied among different vegetation types, thereby impeding accur... Soil respiration (SR) is the second-largest flux in ecosystem carbon cycling. Due to the large spatio-temporal variability of environmental factors, SR varied among different vegetation types, thereby impeding accurate estimation of CO2 emissions via SR. However, studies on spatio-temporal variation of SR are still scarce for semi-arid regions of North China. In this study, we conducted 12-month SR measurements in six land-use types, including two secondary forests (Populus tomentosa (PT) and Robinia pseudoacacia (RP)), three artificial plantations (Armeniaca sibirica (AS), Punica granatum (PG) and Ziziphusjujuba (Z J)) and one natural grassland (GR), to quantify spatio-temporal variation of SR and distinguish its controlling factors. Results indicated that SR exhibited distinct sea- sonal patterns for the six sites. Soil respiration peaked in August 2012 and bottomed in April 2013. The temporal coefficient of variation (CI0 of SR for the six sites ranged from 76.98% to 94.08%, while the spatial CV of SR ranged from 20.28% to 72.97% across the 12-month measurement. Soil temperature and soil moisture were the major controlling factors of temporal variation of SR in the six sites, while spatial variation in SR was mainly caused by the differences in soil total nitrogen (STN), soil organic carbon (SOC), net photosynthesis rate, and fine root biomass. Our results show that the annual average SR and Q10 (temperature sensitivity of soil respira- tion) values tended to decrease from secondary forests and grassland to plantations, indicating that the conversion of natural ecosystems to man-made ecosystems may reduce CO2 emissions and SR temperature sensitivity. Due to the high spatio-temporal variation of SR in our study area, care should be taken when converting secondary forests and grassland to plantations from the point view of accurately quantifying C02 emissions via SR at regional scales. 展开更多
关键词 soil respiration spatio-temporal variation substrate availability temperature sensitivity global carbon cycle North China
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Spatio-temporal Variations in Plantation Forests'Disturbance and Recovery of Northern Guangdong Province Using Yearly Landsat Time Series Observations(1986-2015) 被引量:4
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作者 SHEN Wenjuan LI Mingshi WEI Anshi 《Chinese Geographical Science》 SCIE CSCD 2017年第4期600-613,共14页
Forest disturbance plays a vital role in modulating carbon storage,biodiversity and climate change.Yearly Landsat imagery from 1986 to 2015 of a typical plantation region in the northern Guangdong province of southern... Forest disturbance plays a vital role in modulating carbon storage,biodiversity and climate change.Yearly Landsat imagery from 1986 to 2015 of a typical plantation region in the northern Guangdong province of southern China was used as a case study.A Landsat time series stack(LTSS) was fed to the vegetation change tracker model(VCT) to map long-term changes in plantation forests' disturbance and recovery,followed by an intensive validation and a continuous 27-yr change analysis on disturbance locations,magnitudes and rates of plantations' disturbance and recovery.And the validation results of the disturbance year maps derived from five randomly identified sample plots with 25 km^2 located at the four corners and the center of the scene showed the majority of the spatial agreement measures ranged from 60% to 83%.A confusion matrix summary of the accuracy measures for all four validation sites in Fogang County showed that the disturbance year maps had an overall accuracy estimate of 71.70%.Forest disturbance rates' change trend was characterized by a decline first,followed by an increase,then giving way to a decline again.An undulated and gentle decreasing trend of disturbance rates from the highest value of 3.95% to the lowest value of 0.76% occurred between 1988 and 2001,disturbance rate of 4.51% in 1994 was a notable anomaly,while after 2001 there was a sharp ascending change,forest disturbance rate spiked in 2007(5.84%).After that,there was a significant decreasing trend up to the lowest value of 1.96% in 2011 and a slight ascending trend from 2011 to 2015(2.59%).Two obvious spikes in post-disturbance recovery rates occurred in 1995(0.26%) and 2008(0.41%).Overall,forest recovery rates were lower than forest disturbance rates.Moreover,forest disturbance and recovery detection based on VCT and the Landsat-based detections of trends in disturbance and recovery(LandT rendr) algorithms in Fogang County have been conducted,with LandT rendr finding mostly much more disturbance than VCT.Overall,disturbances and recoveries in northern Guangdong were triggered mostly by timber needs,policies and decisions of the local governments.This study highlights that a better understanding about plantations' changes would provide a critical foundation for local forest management decisions in the southern China. 展开更多
关键词 plantation Landsat dense time series remote sensing forest disturbance and recovery driving forces northern Guangdong
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Interference of Quantum Chaotic Systems in Phase Space 被引量:1
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作者 徐酉阳 《Communications in Theoretical Physics》 SCIE CAS CSCD 2013年第10期453-457,共5页
We investigate the interference of a kicked harmonic oscillator in phase space.With the measure of interference defined in Lee and Jeong[Phys.Rev.Lett.106(2011)220401],we show that interference increases more rapidly ... We investigate the interference of a kicked harmonic oscillator in phase space.With the measure of interference defined in Lee and Jeong[Phys.Rev.Lett.106(2011)220401],we show that interference increases more rapidly in the chaotic regime than in the regular regime,and that the sub-Planck structure is of importance for the decoherence time in the chaotic regime.We also find that interference plays an important role in energy transport between the kicking fields and the kicked harmonic oscillator. 展开更多
关键词 quantum chaos INTERFERENCE kicked harmonic oscillator
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Spatiotemporal variations of aridity in China during 1961–2015: decomposition and attribution 被引量:5
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作者 Chang Liu Wei Huang +2 位作者 Song Feng Jianhui Chen Aifeng Zhou 《Science Bulletin》 SCIE EI CAS CSCD 2018年第18期1187-1199,共13页
Changes in global climate intensify the hydrological cycle, directly influence precipitation, evaporation, runoff, and cause the re-distribution of water resources in time and space. The aridity index (AI), defined ... Changes in global climate intensify the hydrological cycle, directly influence precipitation, evaporation, runoff, and cause the re-distribution of water resources in time and space. The aridity index (AI), defined as the ratio of annual precipitation to annual potential evapotranspiration, is a widely used numerical indicator to quantify the degree of dryness at a given location. This study examined the effects of climate change on Al in China during 1961-2015. The results showed that the nationally averaged AI experienced a notable interdecadal transition in 1993, characterized by increasing AI (wetter) between 1961 and 1993, and decreasing AI (drier) after 1993. Overall, the decreased solar radiation (solar dimming) was the main factor affected the nationally averaged AI during 1961-1993, while the relative humidity dominated the variations of nationally averaged AI during 1993-2015. However, the roles of individual factors on the changes in AI vary in different subregions. Precipitation is one of the important contributing factors for the changes orAl in almost all subregions, except the Mid-Lower Yangtze and Huaihe basins. Solar radiation has been significantly decreased during 1961-1993 in South China, Southwest China, Mid-Lower Yangtze and Huaihe basins, and the Tibetan Plateau. Therefore, it dominated the trends of AI in these subregions. The relative humidity mainly affected the Mid-Lower Yangtze and Huaihe basins, Southwest China, and the Tibetan Plateau during 1993-2015, hence dominated the trends of Al in these subregions. The changes of temperature and wind speed, however, played a relatively weak role in the variations of AI. 展开更多
关键词 ARIDITY The transition of decadal variation Attribution analysis Spatial variation
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Spatio-temporal evolution of drought and flood disaster chains in Baoji area from 1368 to 1911 被引量:5
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作者 万红莲 宋海龙 +2 位作者 朱婵婵 张蓓蓓 张咪 《Journal of Geographical Sciences》 SCIE CSCD 2018年第3期337-350,共14页
Based on the collation and statistical analysis of flood and drought information in Baoji area from 1368 to 1911, and in the context of climate change, we investigated the spatio-temporal evolution characteristics of ... Based on the collation and statistical analysis of flood and drought information in Baoji area from 1368 to 1911, and in the context of climate change, we investigated the spatio-temporal evolution characteristics of drought and flood disaster chains in this area during the Ming and Qing dynasties using the methods of moving average, cumulative anomaly and wavelet analysis. The results are as follows:(1) We found a total of 297 drought and flood events from 1368 to 1911 in Baoji. Among these events, droughts and floods occurred separately 191 and 106 times, which accounted for 64.31% and 35.69% of the total events, respectively.(2) We observed distinct characteristics of flood and drought events in Baoji in different phases. The climate was relatively dry from 1368 to 1644. A fluctuant climate phase with both floods and droughts occurred from 1645 to 1804. The climate was relatively wet from 1805 to 1911. Moreover, we observed a pattern of alternating dry and wet periods from 1368 to 1911. In addition, 3 oscillation periods of drought and flood events occurred around 70 a, 110 a and 170 a, which corresponded to sunspot cycles.(3) We also observed an obvious spatial difference in drought and flood events in Baoji. The northern and eastern parts of Weihe River basin were regions with both frequent droughts and floods.(4) The sequential appearance of drought and flood disaster chains in Baoji from 1368 to 1911 was in response to global climate change. Since the 1760s, global climatic deterioration has frequently led to extreme drought and flood events. 展开更多
关键词 Baoji area drought and flood disaster chain climate change spatio-temporal distribution waveletanalysis
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