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161.
针对测土配方施肥技术中要求快速、便捷、高效地进行土壤养分测试的需求,文章基于浸入式光纤探头、平场凹面全息光栅、二极管线阵检测器开发了一种光纤探头式分光光度计用于土壤养分中非金属元素的快速、准确测试。基于国家计量检定规程JJG 178—2007对紫外、可见、近红外分光光度计的性能检测方法测试的该仪器的波长最大允许误差与波长重复性、基线平直度、透射比最大允许误差与透射比重复性均达到了国标第Ⅲ级别标准,其最小光谱带宽、噪声与漂移、杂散光基本达到了国标第Ⅳ级别标准。基于该仪器测试的土壤硝态氮、铵态氮、有效磷、有效硫、有效硼、和有机质含量与基于商用的国产单光束和进口双光束分光光度计测试的结果呈极显著的线性相关关系,其回归方程的斜率接近于1,且对比数据之间无显著性差异。因此,该光纤探头式分光光度计可用于土壤非金属养分的快速、准确测试。 相似文献
162.
甲基异丁酮萃取-原子荧光光谱法间接测定碘 总被引:1,自引:0,他引:1
在硝酸浓度为0.1mol.L-1介质中,I-和Hg2+能生成稳定的化合物,被甲基异丁酮萃取,原子荧光光谱法测定有机相中的汞,间接得到碘的含量。工作考察了萃取条件以及其他影响因素。在优化的实验条件下,碘的含量在0~12μg.L-1范围内呈良好的线性关系,方法的检出限是0.14μg.L-1,相对标准偏差3.3%,对蛋类样品加标回收率为101.8%~110.4%。 相似文献
163.
Chaos communication based on synchronization of discrete-time chaotic systems 总被引:2,自引:0,他引:2 下载免费PDF全文
A novel chaos communication method is proposed based on synchronization of discrete-time chaotic systems. This method uses a full-order state observer to achieve synchronization and secure communication between the transmitter and the receiver. Further, we present a multiple-access chaotic digital communication method by combining the observer with the on-line least square method. Simulation results are also given for illustration. 相似文献
164.
This paper further investigates the synchronization problem of a new chaotic system with known or unknown system parameters. Based on the Lyapunov stability theory, a novel adaptive control law is derived for the synchronization of a new chaotic system with known or unknown system parameters. Theoretical analysis and numerical simulations show the effectiveness and feasibility of the proposed schemes. 相似文献
165.
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168.
Efficiency enhancement of InGaN based blue light emitting diodes with InGaN/GaN multilayer barriers 下载免费PDF全文
The advantages of InGaN based light-emitting diodes with InGaN/GaN multilayer barriers are studied.It is found that the structure with InGaN/GaN multilayer barriers shows improved light output power,lower current leakage,and less efficiency droop over its conventional InGaN/GaN counterparts.Based on the numerical simulation and analysis,these improvements on the electrical and the optical characteristics are mainly attributed to the alleviation of the electrostatic field in the quantum wells(QWs) when the InGaN/GaN multilayer barriers are used. 相似文献
169.
The process of amorphous silica clusters impact on a crystal silicon substrate is studied by molecular dynamics simulation,
focusing on the energy transfer between clusters and the substrate under different impact conditions such as cluster size,
impact velocity, and incidence angle. The impact process is divided into cluster deformation stage, cluster resilience stage,
and cluster rebound stage according to the courses of energy change during the impact process. The simulation elucidates that
the time of impact process of every cluster is only related to cluster size and is independent of impact velocity and incidence
angle. The translational energy loss of the cluster and the potential energy increment of the substrate during cluster deformation
stage, and the dissipation energy of system are independent of cluster size under the same impact energy and incidence angle.
And the translational energy loss of the cluster during cluster rebound stage changes from energy absorption to energy release
after the incidence angle becomes more than 60°. The rotational energy of the cluster may be omitted when the incidence angle
is less than 15°. The ratios of the rotational energy increment of the cluster, the kinetic energy increment, and the potential
energy increment of the substrate to the translational energy loss of the cluster are obviously influenced by impact conditions.
And the ratios of the increment of the other categories of energy to the translational energy loss of the cluster are not
sensitive to impact conditions. 相似文献
170.
The ratio between the carotenoid and chlorophyll concentrations can indicate the physiology and phenology of plants. Most of the vegetation indices related to the ratio between the carotenoid and chlorophyll contents only consider the reflectance from the adaxial leaf surface. In this study, it was found that the leaf reflectance from the abaxial surface is lower than that of the adaxial surface in the visible wavelength region. On the contrary, the reflectance is higher on the adaxial surface in the near-infrared wavelength region. The difference ratio index resulted in the best correlation with the carotenoid/chlorophyll ratio and was the most robust among all the spectral indices studied when the spectral information on the adaxial and abaxial surfaces was pooled. The result indicated that this index can accurately estimate the carotenoid/chlorophyll ratio because of the insensitivity to the differences between adaxial and abaxial leaf surfaces. 相似文献