Climate change will impact agriculture and food production around the world due to the effects of elevated CO2 in the atmosphere, higher temperature, altered precipitation and transpiration regimes, increased frequenc...Climate change will impact agriculture and food production around the world due to the effects of elevated CO2 in the atmosphere, higher temperature, altered precipitation and transpiration regimes, increased frequency of extreme events, and modified weed, pest and pathogen pressure. Data of this study were collected from primary and secondary sources. Primary sources of data were collected using two sets of structured questionnaires. A total number of three hundred （300） questionnaires were administered on categories of respondents in this study. Results of this study revealed that food crops are the major crops cultivated in the study area, and the effects of climate change on agricultural production results in soil loss, plant nutrient loss, textural change, increase in pest and diseases and poor yield germination etc.. This study therefore recommended that cover trees should be planted, which will provide shade and reduce heat, due to climate change and the preservation of underground water.展开更多
This paper presents a lOGb/s highspeed equalizer as the frontend of a receiver for backplane communication. The equalizer combines an analog equalizer and a twotap decisionfeedback equal izer in a halfrate structure t...This paper presents a lOGb/s highspeed equalizer as the frontend of a receiver for backplane communication. The equalizer combines an analog equalizer and a twotap decisionfeedback equal izer in a halfrate structure to reduce the intersymbolinterference （ISI） of the communication chan nel. By employing inductive peaking technique for the highfrequency boost circuit, the bandwidth and the boost of the analog equalizer are improved. The decisionfeedback equalizer optimizes the size of the CMLbased circuit such as D flipflops （DFF） and multiplex （MUX）, shortening the feedback path delay and speeding up the operation considerably. Designed in the 0. 181μm CMOS technology, the equalizer delivers 10Gb/s data over 18in FR4 trace with 28dB loss while drawing 27mW from a 1.8V supply. The overall chip area including pads is 0. 6 -0.7mm2.展开更多
In this study, observational data from 141 meteorological stations in Northwest China, including temperature, precipitation, dust storm, gale days and wind speed, were analyzed statistically to gain insight of the fea...In this study, observational data from 141 meteorological stations in Northwest China, including temperature, precipitation, dust storm, gale days and wind speed, were analyzed statistically to gain insight of the features of basic climate index and extreme climate events. The results showed that the annual mean temperature and seasonal mean temperature rose significantly, and the rising rate of the annual mean temperature is 0.27℃ per decade; the extreme high temperature days have increased; the interdecadal change of annual precipitation is marked, and the precipitation in winter and summer increased slightly, while decreased slightly in spring and autumn. The annual precipitation increased in the area west of the Yellow River, whereas decreased in the area east of the river. The drought had an increasing trend. There were 17 droughts during 1961-2010, and 10 droughts from 1991 to 2010. The number of droughts in spring and autumn increased, while decreased in summer.展开更多
To enhance the accuracy and efficiency of bridge damage identification,a novel data-driven damage identification method was proposed.First,convolutional autoencoder(CAE)was used to extract key features from the accele...To enhance the accuracy and efficiency of bridge damage identification,a novel data-driven damage identification method was proposed.First,convolutional autoencoder(CAE)was used to extract key features from the acceleration signal of the bridge structure through data reconstruction.The extreme gradient boosting tree(XGBoost)was then used to perform analysis on the feature data to achieve damage detection with high accuracy and high performance.The proposed method was applied in a numerical simulation study on a three-span continuous girder and further validated experimentally on a scaled model of a cable-stayed bridge.The numerical simulation results show that the identification errors remain within 2.9%for six single-damage cases and within 3.1%for four double-damage cases.The experimental validation results demonstrate that when the tension in a single cable of the cable-stayed bridge decreases by 20%,the method accurately identifies damage at different cable locations using only sensors installed on the main girder,achieving identification accuracies above 95.8%in all cases.The proposed method shows high identification accuracy and generalization ability across various damage scenarios.展开更多
文摘Climate change will impact agriculture and food production around the world due to the effects of elevated CO2 in the atmosphere, higher temperature, altered precipitation and transpiration regimes, increased frequency of extreme events, and modified weed, pest and pathogen pressure. Data of this study were collected from primary and secondary sources. Primary sources of data were collected using two sets of structured questionnaires. A total number of three hundred （300） questionnaires were administered on categories of respondents in this study. Results of this study revealed that food crops are the major crops cultivated in the study area, and the effects of climate change on agricultural production results in soil loss, plant nutrient loss, textural change, increase in pest and diseases and poor yield germination etc.. This study therefore recommended that cover trees should be planted, which will provide shade and reduce heat, due to climate change and the preservation of underground water.
基金Supported by the National High Technology Research and Development Programme of China(No.2011AA10305)
文摘This paper presents a lOGb/s highspeed equalizer as the frontend of a receiver for backplane communication. The equalizer combines an analog equalizer and a twotap decisionfeedback equal izer in a halfrate structure to reduce the intersymbolinterference （ISI） of the communication chan nel. By employing inductive peaking technique for the highfrequency boost circuit, the bandwidth and the boost of the analog equalizer are improved. The decisionfeedback equalizer optimizes the size of the CMLbased circuit such as D flipflops （DFF） and multiplex （MUX）, shortening the feedback path delay and speeding up the operation considerably. Designed in the 0. 181μm CMOS technology, the equalizer delivers 10Gb/s data over 18in FR4 trace with 28dB loss while drawing 27mW from a 1.8V supply. The overall chip area including pads is 0. 6 -0.7mm2.
基金supported by the Special Project on Climate Change in China Meteorological Administation(No. CCSF2010-5)
文摘In this study, observational data from 141 meteorological stations in Northwest China, including temperature, precipitation, dust storm, gale days and wind speed, were analyzed statistically to gain insight of the features of basic climate index and extreme climate events. The results showed that the annual mean temperature and seasonal mean temperature rose significantly, and the rising rate of the annual mean temperature is 0.27℃ per decade; the extreme high temperature days have increased; the interdecadal change of annual precipitation is marked, and the precipitation in winter and summer increased slightly, while decreased slightly in spring and autumn. The annual precipitation increased in the area west of the Yellow River, whereas decreased in the area east of the river. The drought had an increasing trend. There were 17 droughts during 1961-2010, and 10 droughts from 1991 to 2010. The number of droughts in spring and autumn increased, while decreased in summer.
基金The National Natural Science Foundation of China(No.52361165658,52378318,52078459).
文摘To enhance the accuracy and efficiency of bridge damage identification,a novel data-driven damage identification method was proposed.First,convolutional autoencoder(CAE)was used to extract key features from the acceleration signal of the bridge structure through data reconstruction.The extreme gradient boosting tree(XGBoost)was then used to perform analysis on the feature data to achieve damage detection with high accuracy and high performance.The proposed method was applied in a numerical simulation study on a three-span continuous girder and further validated experimentally on a scaled model of a cable-stayed bridge.The numerical simulation results show that the identification errors remain within 2.9%for six single-damage cases and within 3.1%for four double-damage cases.The experimental validation results demonstrate that when the tension in a single cable of the cable-stayed bridge decreases by 20%,the method accurately identifies damage at different cable locations using only sensors installed on the main girder,achieving identification accuracies above 95.8%in all cases.The proposed method shows high identification accuracy and generalization ability across various damage scenarios.
