基于反射率及导数的草原植被冠层光合有效吸收分量高光谱反演

利用ASD便携式野外光谱仪和光量子仪实测了6种草原植被类型关键生育期的反射光谱数据和光合有效辐射值,利用可见光波段处反射率及近红外波段区处一阶导数分别与fPAR建立逐步回归方程,同时,将各波段反射率与各波段导数光谱建立逐步回归方程。结果表明:典型草原光合有效辐射分量与可见光反射率相关性好于近红外波段反射率,其中在405和470nm波段相关性最好;fPAR与一阶导数相关关系在855和965nm波段处较强。fPAR与405和470nm反射率以及965nm一阶导数的多波段逐步回归分析结果取得了较单波段和NDVI最优的估算效果,R2达0.939。利用高光谱数据进行fPAR估算时,需要综合考虑可见光和近红外波段信息,同时也要充分考虑反射率与反射率导数的方法。水分强吸收的光谱波段具有提高fPAR估算精度的潜力。

基于不同植被指数的棉花光合有效辐射吸收分量估算研究

通过开展小区棉花密度和水分对比试验,分析不同密度和水分处理的棉花整个生育期光合有效辐射吸收分量(FPAR)与光谱反射率的相关关系,建立棉花FPAR光谱估算模型。结果表明,棉花FPAR与选取的所有植被指数均呈极显著相关,其中绿度植被指数(GREENNDVI)和反射率比值(GMI)与FPAR的相关性最好,相关系数(r)分别为0.794和0.765。分别用GREENNDVI和GMI建立棉花FPAR的估算模型,其决定系数(r2)分别为0.657和0.633,均方根误差(RMSE)分别为0.089和0.093。研究表明,利用光谱特征参数可以有效地估算棉花整个生育期的FPAR。

植被光合有效辐射吸收分量及最大光能利用率算法的改进

植被冠层对入射光有效辐射的吸收系数(FPAR)和最大光能利用率是NPP模拟的重要参数。利用光量子仪实测了典型草原植被类型关键生育期光合有效辐射值,根据NDVI与FPAR之间的良好相关性,建立了2个FAPR估算模型。结果表明,实测的FPAR值与模型估算的FPAR之间的相关性均达到极显著水平,2个模型的估测值之间没有显著性差异。因此,本研究中采取求均值后计算了我国草原的FPAR,并与NASA-FPAR产品进行了嵌套和互补,形成全国完整的草原FPAR空间分布图。同时,基于归一化植被指数和叶面积指数,以中国草原18大类分类结果为基础单元,对中国草原18大类的最大光能利用率进行调整,调整后的最大光能利用率输入NPP模型后,改善了NPP估算精度,在大类尺度上,总体预测精度为85.71%。

大针茅典型草原冠层光合有效辐射各分量变化规律分析

利用光量子仪实测了大针茅典型草原植被类型关键生育期光合有效辐射值,分析了入射PAR、冠层反射PAR、透射PAR、土壤反射PAR与FPAR的变化规律。结果表明,入射与透射PAR呈较标准正弦曲线变化、而冠层反射与土壤反射PAR呈不太平滑的正弦曲线变化,最大值均出现在中午12:30左右;FPAR曲线开口方向与PAR的开口方向相反,呈较标准的余弦曲线变化,最小值出现在中午11:30左右;且日均FPAR值可用一天内的上午9:30或下午14:30的瞬时值来替代;NDVI、LAI与FPAR均呈线性关系,且R^2分别达到0.87、0.7。

城市群花粉过敏网络关注度及影响因素研究

研究花粉过敏网络关注度时空特征及影响因素有利于掌握相关信息,服务民生。本文结合百度指数、气象、遥感数据,分析8个城市群2017—2021年花粉过敏网络关注度时空特征与影响因素,并采用随机森林、反向传播神经网络模型进行模拟。结果表明:(1)时空特征:关注度每年高峰期在春季(4—5月);人口聚集的城市最高,在空间上聚集,京津冀、山东半岛、长三角、珠三角城市群为热点区。(2)与影响因素关系:有效范围内,温度升高、短时雷暴雨、空气质量差、光合有效辐射吸收分量升高、夜间灯光强,关注度高;高湿、高风速、大雨、久雨,关注度低;夜间灯光相关性最高。(3)城市群方面:北方城市群的温度、沿海城市群的湿度、地形起伏大城市群的风速、南方城市群的降水、珠三角和长三角城市群的空气质量指数、珠三角和京津冀城市群的光合有效辐射吸收分量重要性大,夜间灯光都不可替代。(4)随机森林和反向传播神经网络适用于模拟关注度,各城市群R^(2)均在0.64~0.92之间,RMSE、MAE均在1以下,反向传播神经网络比随机森林模拟效果更好。成渝城市群2个模型拟合度均优,其次是京津冀、珠三角和长江中游城市群。本文的方法和结果可为花粉过敏相关工作提供参考。

频率调制光谱稳频法的信号处理算法研究

频率调制光谱稳频法利用参考气体对激光吸收量来反馈控制激光波长稳定,反馈信号的提取通过调节参考信号与吸收分量同相的方式实现。为免除移相的麻烦,提出利用吸收分量和色散分量的合成信号作为反馈信号,通过仿真证明可以利用合成信号作为反馈信号。该合成信号的提取利用两正交参考信号与合成信号耦合的方式实现,该方式方便了信号的提取,免除了调相的麻烦。最后还提出一种判定激光波长偏移的方法。

落叶阔叶林冠层非光合组分对冠层FPAR的影响分析——一种分层模拟的方法

估算并消除冠层非光合组分(non-photosynthetic vegetation,NPV)吸收的光合有效辐射,对准确估算生态系统总初级生产力(gross primary productivity,GPP)具有重要意义。以落叶阔叶林为例,通过设置不同情景,应用任意倾斜叶片散射(scattering by arbitrary inclined leaves,SAIL)模型进行冠层光合有效辐射吸收分量(fraction of absorbed photosynthetically active radiation,FPAR)的分层模拟,分析冠层NPV的FPAR的变动及其对冠层FPAR的贡献,并初步探讨落叶阔叶林NPV的FPAR的估算方法。结果表明,冠层NPV的FPAR的大小与冠层结构相关,在高覆盖度植被区NPV对冠层FPAR的贡献通常较小,但在低植被覆盖区的贡献会较高;NPV降低了冠层在近红外波段的反射;增强型植被指数(enhanced vegetation index,EVI)与NPV的FPAR存在显著的线性负相关关系,可用来描述NPV的变化。

Determination of the Trace Element Contents in Plants Using Atomic Absorption Spectrophotometer

The aim of the study is to investigate the contents of trace element Se, Cd, Pb in three plants including burdock, ginkgol and garlic via graphite furnace atomic absorption and standard addition method. The results show that Se in burdock stem, skin and leaf are 32.40, 48.63, 38.10 μg/g, respectively; Cd in burdock stem, skin and leaf are 0. 160 0, 0. 300 0, 0. 140 0 μg/g, respectively; Cd in burdock stem, skin and leaf are 2. 020, 3. 960, 2. 410 μg/g, respectively. In the ginkgo and ginko leaf, Se contents are 17.63 and 16.91 μg/g, respectively ; for Cd are 0. 181 0 and 0.2020μg/g, respectively ; for Pb are 3. 572 and 4. 021 μg/g, respectively. In garlic, Se, Cd and Pb are 73. 900 0, 6. 900 0 and 0. 390 0, respectively. All the standard deviations of measured results are below 2.3%, recovery rate are from 99% to 101%.

Monolithic Integration of Electro-Absorption Modulators and DFB Lasers by Modified Double Stack Active Layer Approach

Monolithic electro absorption modulated distributed feedback(DFB) lasers are proposed and fabricated by using a modified double stack active layer.The 38mA threshold,9dB extinction ratio (from 0 5V to 3 0V),and about 5mW output power at the 100mA operation current are achieved.Compared with other reported results (only 1 5mW at the same operation current) of the traditional stack active structure,the proposed structure improves the output power of devices.

Mass Transfer Enhancement of Gas Absorption by Adding the Dispersed Organic Phases

Mass transfer enhancement of gas absorption by adding a dispersed organic phase has been studied in this work. Various dispersed organic phases （heptanol, octanol, isoamyl alcohol, heptane, octane, and isooctane） were tested respectively in the experiment. According to the theoretical model and experimental data, the overall volumetric mass transfer coefficient and enhancement factor were obtained under different dispersed organic phase volume fraction and stirring speed. The experimental results indicate that gas-liquid mass transfer is enhanced at different level by adding a dispersed organic phase. The best performance of enhancement were achieved with the dispersed organic phase volumetric fraction of 5% and under an intermediate stirring speed of 670 r·min^-1. Among the organic phases tested in the experiment, alcohols show better performance, which gave 20% higher enhance-ment of overall volumetric mass transfer coefficient than adding alkanes.

Effects of temperature,algae biomass and ambient nutrient on the absorption of dissolved nitrogen and phosphate by Rhodophyte Gracilaria asiatica

Gracilaria asiatica, being highly efficient in nutrient absorption, is cultivated in sea cucumber ponds to remove nutrients such as nitrogen and phosphate. It was cultured in a laboratory simulating field conditions, and its nutrient absorption was measured to evaluate effects of environmental conditions. Ammonia nitrogen （AN）, nitrate nitrogen （NN）, total inorganic nitrogen （TIN）, and soluble reactive phosphorus （SRP） uptake rate and removal efficiency were determined in a 4~2 factorial design experiment in water temperatures （T） at 15~C and 25~C, algae biomass （AB） at 0.5 g/L and 1.0 g/L, total inorganic nitrogen （TIN） at 30 ~tmol/L and 60 ~tmol/L, and soluble reactive phosphorus （SRP） at 3 and 6 ~tmol/L. AB and ambient TIN or SRP levels significantly affected uptake rate and removal efficiency of AN, NN, TIN, and SRP （P〈0.001）. G. asiatica in AB of 0.5 g/L showed higher uptake rate and lower removal efficiency relative to that with AB of 1.0 g/L. Nitrogen and phosphorus uptake rate rose with increasing ambient nutrient concentrations; nutrient removal efficiency decreased at higher environmental nutrient concentrations. The algae preferred to absorb AN to NN. Uptake rates of AN, NN, and SRP were significantly affected by temperature （P〈0.001）; uptake rate was higher for the 25~C group than for the 15~C group at the initial experiment stage. Only the removal efficiency of AN and SRP showed a significant difference between the two temperature groups （P〈0.01）. The four factors had significant interactive effects on absorption of N and P, implying that G. asiatica has great bioremedial potential in sea cucumber culture ponds.

An experimental inter-comparison of radiotherapic dosimetric delivery to assess X-Ray linear accelerator output characteristics

The dosimetric inter-comparison studies carry pertinent significance to ensure uniform radiation dose delivery for clinical trials. This paper investigates the comparative performance analysis of an X-ray high power linear accelerator per- formed by the International Dosimetry Survey Mission and Institute of Nuclear Medicine ＆ Oncology （INMOL）, Lahore. The measurements were made using cylindrical ionization chambers based on the International Atomic Energy Agency （IAEA） TRS-398 protocol for absorbed dose-to-water dosimetric standards, and the percentage deviation was found to be between 0.5 % - 1%. The dosimetric analysis concerning linear X-ray accelerator output performed by INMOL, Lahore was found to be in good agreement with the results of IAEA Dosimtery Survey Mission.

Development of 2D Temperature and Concentration Measurement Method Using Tunable Diode Laser Absorption Spectroscopy

Exhaust gas temperature is an important factor in NOx, THC and PM emissions of engines. Especially 2D temperature and concentration distribution plays an important role for the engine efficiency. A thermocouple is intrinsically a point temperature measurement method and noncontact 2D temperature distribution cannot be attained by thermocouples. Recently, as a measurement technique with high sensitivity and high response, laser diagnostics has been developed and applied to the actual engine combustions. With these engineering developments, transient phenomena such as start-ups and load changes in engines have been gradually elucidated in various conditions. In this study, the theoretical and experimental research has been conducted in order to develop the noncontact and fast response 2D temperature and concentration distribution measurement method. The method is based on a Computed Tomography （CT） method using absorption spectra of water vapor at 1388 nm. It has been demonstrated that the method has been successfully applied to engine exhausts to measure 2D temperature distributions.

Microwave absorbing properties of high titanium slag

Microwave absorbing properties of high titanium slag were investigated by using microwave cavity perturbation technique. High titanium slag containing more than 90% TiO2 was prepared by carbothermal reduction of ilmenite. The temperature rise curve of high titanium slag in microwave heating process was obtained. Crystalline compounds of high titanium slag before and after microwave irradiation were obtained and characterized by X-ray diffractometry （XRD）. Effects of particle size of high titanium slag anal mixtures of high titanium slag with different mass fractions of V2o5 on microwave absorbing properties were investigated systematically. The results show that high titanium slag has good microwave absorption property; untreated high titanium slag mainly consists of crystalline compounds of anatase and iron titanium oxide, while the microwave-irradiation treated one is mainly composed of crystalline compounds of rutile and irgn titanium oxide. Synthetic anatase is transformed completely into rutile at about 1 050 ℃ for 20 min under microwave irradiation. High frequency shift and low amplitude of voltage make high titanium slag an ideal microwave absorbent. 180 μm of particle size and 10% mass fraction of V2O5 are found to be the optimum conditions for microwave absorption.

Effect of Se-S Cooperated Application on the Mineral Content and Nutrition Quality of Garlic （Allium Sativum L.）

Eleven nutrition elements and 5 quality elements of garlic （Allium sativum L.） in different Se, S level and their interaction pot experiments were analyzed by atom absorbing spectrophotometer, titration and fixing sulfur method. The mineral elements were analyzed by the Principal Component Analysis and the Factor Analysis on the SPSS 10.0 and three main factors were picked. The results showed that Se, S and Se-S cooperated application enhanced the garlic nutrition quality by increasing mineral nutrition. The garlic Vc was the highest after using higher Se compared middle S level （S 20 mg/kg soil ＋ Se 40 mg/kg soil）. Lower Se level compared middle S level （S 40 mg/kg soil ＋ Se 20 mg/kg soil） get the highest garlic abio-Se in all treatments. The garlic organic Se content was the highest after using higher Se compared middle S （S 40 mg/kg soil ＋ Se 40 mg/kg soil）. The treatment lower S compared lower Se level get the highest garlic allicin in all treatment. It showed that the fresh eating factor was affected by the element Se. The flavor factor and health care factor were affected by both Se and S.

Spatio-temporal Distributions of Tropospheric NO_2 over Oases in Taklimakan Desert, China

Soil biogenic NO emission is one of the most important sources of atmospheric nitrogen oxides(NOx) worldwide. However, the estimation of soil source, especially in arid areas presents large uncertainties because of the substantial lack of measurements. In this study, we selected the Ruoqiang oases on the southeastern edge of the Taklimakan Desert, China as the study area and applied Ozone Monitoring Instrument(OMI) NO2 retrievals(DOMINO v2.0, 2005–2011) to investigate the spatial distribution and seasonal variations in tropospheric NO2 vertical column density(VCD). High NO2 VCDs were observed over the oases(farmlands and natural vegetation), with the highest value obtained during summer, and lowest during winter. Pulses were observed during spring. We conducted in-situ measurements in June 2011 in Milan oasis and employed ground-based multi-axis differential optical absorption spectroscopy(MAX-DOAS) instruments to validate satellite NO2 retrievals. The findings are as follows: 1) in the study area soil biogenic NO emission is the dominant source of tropospheric NO2; 2) oases(farmlands) are hotspots of tropospheric NO2, and a higher increase in tropospheric NO2 is found in oases from winter to summer; and 3) enhancement of soil biogenic NO emission due to soil managements is predictable. Given the rapid agricultural development in the southern Uygur Autonomous Region of Xinjiang, researches on soil biogenic NO emission and increase in tropospheric NOx should be given more importance.

Correlation between coal characteristics and methane adsorption on China＇s coals

It is highly important to investigate relationship between coal characteristics and methane adsorption on coal in the fields of coalbed methane recovery. Based on data examination of coal quality indexes collected from the literatures, regression equations for Langmuir adsorption constants, VL or VLIPL, and coal quality indexes for selected coal samples were developed with multiple linear regression of SPSS software according to the degree of coal metamorphosis. The regression equations built were tested with data collected from some literatures, and the influences of coal quality indexes on CH4 adsorption on coals were studied with investigation of regression equations, and the reasons of low accuracy to Langmuir constants calculated with regression equation for a few coal samples were investigated. The results show that the regression equations can be employed to predict Langmuir constants for methane adsorption isotherms on coals obtained using volumetric gas adsorption experiments, which are conducted at 30 ℃ on a wet or dried coal samples with less than 30% ash content in coal. The influence of same coal quality index with various coal rank or influence of various coal quality indexes for same coal rank on CH4 adsorption is not consistent. The regression equations have different accuracy to different coal rank, in which the VL equations supply better prediction accuracy for anthracite and higher prediction error for lower metamorphosis coal, and the PL prediction error with VL and VL/PL equations is lower to bituminous coal and higher to anthracite.

Measurement and Modeling for the Solubility of Hydrogen Sulfide in Primene JM-T

The primary aliphatic amine Primene JM-T was investigated as a potential absorbent for H2S removal. The solubility of HzS in JM-T was measured at 298, 313,333,353, and 368 K with H2S partial pressures from 20 to 760 kPa and HzS loading from 0.02 to 0.8 mol H2S per mol JM-T. Relevant physical properties, such as density, viscoslty and dielectric constant, ot the matenal were measured. ＇The thermodynamlc model with two-suttlX Margules equation was used to correlate the experimental vapor-liquid equilibrium data. Furthermore, the absorption mechanism in non-aqueous system is suggested and the difference between non-aqueous and aqueous absorption system is pointed out.

Sensory and Organoleptic Characteristic, Zinc and Iron Content of Fortified Chips from Cassava Flour

Iron fortification can cause several biophysicochemical modifications. Those depend on many factors, such as iron fortificant and the food carrier. There were four groups of chips： 1） non-fortified wheat flour chips （K1）; 2） non-fortified cassava flour chips （K2）; 3） fortified cassava flour chips, each with ZnSO4 30 ppm and NaFe EDTA （K3） 30 ppm and 4） fortified cassava flour chips, each with ZnSO4 50 ppm and NaFe EDTA （K4） 50 ppm. The chips were evaluated for sensory characteristic （color, taste, flavor, and texture）, organoleptic characteristics tested by preference test, as well as zinc and iron contents. Zinc and iron contents were analyzed by Atomic Absorption Spectophotometric method. The results showed that both fortificants did not affect the sensory characteristic of cassava flour chips. The preference test showed that color, taste, and flavor of Kl chips as a control, were mostly liked, but there was no significant difference preference of texture. Moreover, preference test using K2 as control showed that color of K3 was mostly liked, but there was no significant difference preference of taste, flavor and texture. Fortification can increase the contents of zinc and iron in cassava flour chips. The panelist can accept the fortified cassava chips as well as wheat flour chip, as a consequence, both can be a potential way to combat the iron deficiency anemia.

Study on Fractionated Total Body Irradiation before Hematopoietic Stem Cell Transplantation

OBJECTIVE To observe the dose and the complicationsfrom total body irradiation before hematopoietic stem celltransplantation.METHODS This study involved 312 patients with total bodyirradiation before hematopoietic stem cell transplantation. Theywere entered into the treated research from May 1999 to October2005. All patients had received the irradiation from ^(60)Co of anabsorbed dose rate of (5.2 ± 1.13) cGy/min. The total dose of TBIwas 7～12 Gy, 1 f/d × 2 d. A high-dose rate group (≥10 Gy) included139 cases and a low-dose rate group (< 10 Gy) included 173 cases.RESULTS The probability of acute gastrointestinal reactionsin the high-dose rate group was more compared with that in thelow-dose rate group. The differences for other reactions, such ashematopoietic reconstitution and graft survival rate, between thetwo groups were insignificant.CONCLUSION Using fractional total body irradiation at a doserate of 5 cGy/min, with a total dose of 7～12 Gy, 1 f/d × 2 d , withthe lung receiving under 7.5 Gy is a safe and effective pretreatmentfor hematopoietic stem cell transplantation.