金属包覆多层ATR 生物传感器的理论研究􀀂

利用衰减全反射(ATR)方法进行角度探测,通过改进传统传感器只用单层金属膜激发表面等离子波(SPR)进行探测的结构设计,利用金属包覆波导代替原来的单层的金属膜结构,并从理论上分析了和计算了金属包覆多层ATR生物传感器的检测机理,从而为研制高灵敏度、高解析力的ATR生物传感器提供了理论依据.     

A model to estimate the path loss in areas with foliage of trees

This paper presents an empirical model to predict attenuation in forest environments considering parameters related to vegetation. Typically, environmental parameters are only included in theoretical models, but they are more difficult to apply. The developed model uses tree density, average tree canopy diameter and foliage density as input parameters. The foliage density is very difficult to determine since it depends on the characteristics of trees. A simple metric of this parameter was obtained by measuring the background light silhouetted by the canopy. The model was developed with measurements obtained in different forest environments for two frequencies within the UHF band (Ultra High Frequency). A procedure was also applied to extend the operating frequency range of the model.     

Predicting the principal strong ground motion parameters: A deep learning approach

In this research, new models are developed to estimate the three principal time-domain parameters of seismic ground motion. A novel deep learning (DL) approach coupled with artificial neural network (ANN), namely deep neural network (DNN) is employed for predicting the strong ground motion parameters such as peak ground acceleration (PGA), peak ground velocity (PGV) and peak ground displacement (PGD). This robust technique that has extended the applications of conventional neural networks improves learning of complicated and nonlinear features via increasing the number of layers as well as the neurons in each layer. The proposed models are constructed upon the NGA-West2 database provided by PEER (Pacific Earthquake Engineering Research Center). This database is more comprehensive than NGA-West1 which was mainly considered for developing previous artificial intelligence-based prediction models. Therefore, the new models are more reliable and can be used for wider ranges of predictors. The DNN attenuation models yield accurate estimates of the site PGA, PGV and PGD based on earthquake magnitude, rake angle, source to site distance and soil shear wave velocity. In addition, it is shown that the developed models, with correlation coefficients of 0.902, 0.899 and 0.911 (for PGA, PGV and PGD respectively), outperform the existing soft computing models. Furthermore, the average values of error measures such as MAE, MAPE and RMSE for PGA, PGV and PGD equal to 0.456, 0.758 and 0.581 compare favorably with those of previous models.     

Portable spectroscopic fast neutron probe and 3He detector dead-time measurements

This paper presents dead-time calculations for the Portable Spectroscopic Fast Neutron Probe (N-Probe) using a combination of the attenuation law, MCNP (Monte Carlo N-particle Code) simulations and the assumption of ideal paralyzing and non-paralyzing dead-time models. The N-Probe contains an NE-213 liquid scintillator detector and a spherical ³He detector. For the fast neutron probe, non-paralyzing dead-time values were higher than paralyzing dead-time values, as expected. Paralyzing dead-time was calculated to be 37.6 μs and non-paralyzing dead-time was calculated to be 43.7 μs for the N-Probe liquid scintillator detector. Dead-time value for Canberra ³He neutron detector (0.5NH1/1K) was also estimated using a combination of subcritical assembly measurements and MCNP simulations. The paralyzing dead-time was estimated to be 14.5 μs, and the non-paralyzing dead-time was estimated to be 16.4 μs for ³He gas filled detector. These results are consistent with the dead-time values reported for helium detectors.     

运行中110kV变压器的噪声特性

针对运行中的主变压器,开展其噪声的距离衰减、高度衰减、频谱特性及负荷关系等方面的特性试验,分析了主变噪声的主要特征和传播规律,探讨了其环境影响模式。     

光纤到户工程用户光缆的验收测试

依据国家标准和IEC标准中关于光纤到户工程用户光缆的设计和施工验收相关规定,介绍住宅建设方负责施工的用户光缆部分的验收测试指标的要求、测试方法的选择以及测试仪表的使用,包括用户接入点与工程界面的划分;用户光缆光链路的构成和传输指标;采用光源光功率计测试光纤链路衰减指标的方法等。     

Power-aware routing based on DSR for Mobile Ad hoc NETworks

Energy consumption is a crucial design concern in Mobile Ad hoc NETworks （MANETs） since nodes are powered by batteries with limited energy, whereas Dynamic Source Routing （DSR） protocol does not take the energy limitation of MANET nodes into account. This paper proposes an energy-saving routing algorithm based on DSR： Power Aware Routing protocol based on DSR （PAR-DSR）. The design objective of PAR-DSR is to select energy-efficient paths. The main features of PAR-DSR are： （1） Nodes use the Signal Attenuation Rate （SAR） to conduct power control operations; （2） Minimum path cost as metric to balance the traffic and energy consumption of wireless nodes. The simulation results show that PAR-DSR can greatly reduce the energy consumption of MANET nodes. The average node lifetime of PAR-DSR is 50%-77% longer than that of DSR.     

Attenuation correction of polychromatic L-shell X-ray fluorescence computed tomography imaging

Polychromatic L-shell X-ray fluorescence computed tomography is a promising imaging technique to explore the element distribution of the sample. However, the image quality of large samples would be decreased dramatically due to the present of the self-absorption. In this investigation, an attenuation correction algorithm based on theories related to X-ray fluorescence was proposed. With this method, the attenuation coefficients at the incident energies were expressed as a function of known X-ray energies and unknown platinum concentrations. Then the attenuation coefficients were calculated based on the theories and added in the contribution value of the pixel in Maximum Likelihood Expectation Maximization reconstruction method. The element distributions can be got through continuous iterations. Finally, the feasibility of this method was tested by Monte Carlo simulation. The results indicated that, for a 4-mm diameter phantom containing an object of 2 mm in diameter with 0.10 wt% platinum solutions, the CNR of reconstructed images increased from 53.5 to 203.8 after attenuation correction while the relative error decreases from 97% to 2%.     

岩石中应力弛豫的衰减和模量色散

本文在低频和声频范围内研究了砂岩、大理岩及花岗岩在不同饱和液体情况下的衰减和模量随温度的变化，同时还探讨了衰减与激发频率、共振振幅的关系。并根据时温等效原理，得出了饱和原油砂岩在衰减～温度港上28℃的衰减峰应该与衰减～频率港上8．9HZ的衰减峰相对应的结论。     

区域中心的建筑几何诠释 评析普雷斯顿·斯科特·科恩的南京大学仙林校区学生活动中心设计

普雷斯顿·斯科特·科恩设计的南京大学仙林校区学生活动中心,通过建筑几何对具有向心性和终极性特征的校区核心建筑进行了诠释:内含作用力因果关系的几何体系表达了一种介于随意性和象征性之间的向心控制性;基于该体系的形态拉伸演变和丰富了建筑的时空体验,并以时间过程性重新定义终极性。设计对当地建造技术与经济现状的充分结合使这种诠释更具本土性。