应用运动平均斜率模型模拟农林复合系统土壤水分动态的研究

根据MOLDRUP等(1989)提出的运动平均斜率(MMS)模型,考虑源汇项,在入渗和蒸发交替的条件下,对半干旱平原农区农林复合系统中土壤水分运动进行数值模拟,结果表明:模拟值与实测值吻合效果较好,并体现了该模型的简洁、快速等优点。由此表明,MMS模型具有较强的适用性,可为农林复合系统土壤水分运移、耗水特征以及水分效应的定量研究提供准确合理的理论计算依据。     

陕西省粮食生产与粮食安全趋势预测

基于移动平均法,应用陕西省近31 a粮食产量数据对其未来10a粮食综合生产潜力进行了短期预测.结果表明:陕西省粮食单产提升幅度较小,年均每公顷增长46.2 kg;粮食总产上升缓慢,年均增长10万t;在粮食产量构成中,小麦产量及其比例下降,玉米产量及其比例上升,水稻与大豆产量及其比重变化较小;各粮食作物单产均稳步提升;人...     

Temporal association of potato tuber development with susceptibility to common scab and Streptomyces scabiei‐induced responses in the potato periderm

Using hydroponics and novel non‐destructive pot culture systems which enable inoculation at specific tuber development stages, the dynamics of common scab infection patterns in potato were studied in order to provide more precise identification of tuber physiological factors associated with susceptibility. At the whole‐tuber level, infection percentages were greatest when Streptomyces scabiei inoculation occurred early; at 2 weeks after tuberization (WAT) 68% of tubers became infected, contrasting with late inoculation (8 WAT), when only 4% infection occurred. The first‐formed internodes were most susceptible to infection, whilst later‐forming and slower‐expanding internodes were less susceptible. Detailed tuber physiological examination of internode 2 showed that pathogen‐induced changes, including increased phellem (periderm) thickness, cell layers and phellem suberization (key physiological features believed critical to S. scabiei infection) were promoted through S. scabiei inoculation. Sequential harvesting showed enhanced phellem suberization (28% greater than the control) within 7 days of pathogen exposure, while phellem thickness and layer responses were also initiated early in the infection process (10–14 days after pathogen exposure) and these responses were independent of symptom expression. Differences in cultivar response were observed, with greater phellem suberization observed 10 days after tuberization (DAT) in the common‐scab‐tolerant cv. Russet Burbank than in the susceptible cv. Desiree. Likewise, Russet Burbank had thicker and more numerous cell layers in the phellem (up to eight cell layers) during early tuber growth (20–30 DAT) than Desiree (up to six cell layers).     

辽宁省海洋渔业产量结构调整的初步研究

根据辽宁省海洋渔业统计资料,分析了辽宁省海洋渔业产量结构,运用剩余产量模型估算了最大持续产量,运用ARIMA(pdq)时间序列模型与GM(11)模型分析预测了2004～2010年海水养殖产量、远洋渔业产量与各海区的捕捞产量。结果表明:辽宁省近海捕捞产量已经超过最大持续产量,如不采取有效措施仍将有一定程度的增长,在渤海与黄海的产量到2010年将比2003年增加23.40万t与23.79万t;远洋渔业与海水养殖业,其产量在2010年将比2003年增加8.59万t与242.40万t。文章对辽宁省海洋渔业产量结构调整进行了讨论。     

The optimized Gabor window spectrum of gear fault diagnosis detection

There is a lot of non-stationary signals in gear vibration signals,which is analyzed by using Gabor spectrum. To resolve the problem of the choice of window,a method based on entropy is proposed to select the optimal Gabor window width,and the time-frequency resolution of Gabor transform is improved. Since the spectrum has its specific mechanism of crossing-item,the Gabor spectrum is calculated in the region of the key support area and the crossing-item is effectively removed,then the Gabor spectrum is used to analysis the time-frequency distribution of vibration signals of gear,and this method is compared with traditional analysis methods. The result shows that the Gabor spectrum can intuitively react abnormal gear and energy changes with time,and easily diagnose the gear fault.     

Online MW-MSPCA data-driven fault diagnosis

To track the non-stationary dynamics of the process which contains time-varying and multi-scale data, an online moving window multi-scale principal component analysis（MW-MSPCA） data-driven-based fault diagnosis method is proposed. In this data-driven diagnosis technique, wavelet threshold denoising is used to solve the conflict between the statistical model deviation and data correlation decreasing. The statistical models are updated by using moving window principal component analysis in various scales. The contribution of individual process variable to the process behavior change is illustrated in a 3-dimensional contribution chart. A quantitative evaluation mechanism is also given to evaluate the diagonising accuracy. The numerical experimental results for 6135D diesel demonstrate that the proposed method can diagnose sensor fault better in terms of false rejection, false alarm and diagnosing accuracy for fault diagnosis upon comparing with conventional multi-scale principal component analysis（MSPCA） and adaptive multi-way principal component analysis（AMPCA） modeling.     

Regional and circadian variations of sweating rate and body surface temperature in camels (Camelus dromedarius)

It was the aim of this study to investigate the regional variations in surface temperature and sweating rate and to visualize body thermal windows responsible for the dissipation of excess body heat in dromedary camels. This study was conducted on five dromedary camels with mean body weight of 450 ± 20.5 kg and 2 years of age. Sweating rate, skin and body surface temperature showed significant (P < 0.001) circadian variation together with the variation in ambient temperature. However, daily mean values of sweating rate, skin and body surface temperature measured on seven regions of the camel body did not significantly differ. The variation in body surface temperature compared to the variation in skin temperature was higher in the hump compared to the axillary and flank regions, indicating the significance of camel's fur in protecting the skin from daily variation in ambient temperature. Infrared thermography revealed that flank and axillary regions had lower thermal gradients at higher ambient temperature (T_a) and higher thermal gradients at lower T_a, which might indicate the working of flank and axillary regions as thermal windows dissipating heat during the night. Sweating rate showed moderate correlation to skin and body surface temperatures, which might indicate their working as potential thermal drivers of sweating in camels.     

3-D Dynamic Response of Reinforced Embankment and Track System Subjected to Moving Traffic Load

An analytic method was used to study the dynamic response of track system on reinforced embankment subjected to moving traffic load. Based on Biot's dynamic poro-elastic theory, dynamic analytical model of track system and reinforced embankment was established. The rails were described as an infinitely long Euler beam subjected to moving axle loads and sleepers were represented by continuous mass. Reinforced embankment embedded between track system and poro-elastic subsoil was modeled as a transversely isotropic layer. Subsoil was fully saturated poroelastic medium governed by the Biot's theory. Using the Fourier transform, the governing equations were then solved analytically in the frequency-wave-number domain. The time domain responses were obtained by the inverse Fourier transform computation. The influences of the train velocity, thickness of reinforced layer, load amplitude and reinforcement's ratio on the displacement responses of rails were carefully investigated. Computed results show that the vertical displacement of rails increases with the increase of load speed initially and decreases later. The displacement of rails with reinforced embankment is less than the ones without reinforced embankment. The displacement of rails increases with the increase of load amplitude and decreases with the increase of reinforcement's ratio.