Study on effective probe depth of optical coherence tomography system by Monte Carlo simulation

The intensities of Class I and Class II signals at several different probing depths and different coherence lengths are analyzed using a Monte Carlo model with a pencil beam, and the result shows that the longitudinal resolution has influence on the effective probe depth. A Monte Carlo model for optical coherence tomography system with a focused Gaussian beam is proposed. The intensities of Class I and Class II signals at different probing depth for different radius and depth of focus of the beam are simulated using this model. We found that increasing of the depth of focus and decreasing of the beam radius can finitely increase effective probing depth. When the effective probing depth is fixed, optimal signal intensity can be achieved by altering the beam radius or the depth of focus.     

核装置机械部件设计和建造规则中 1、2和3级设备设计要求差异分析

核装置机械部件设计和建造规则(RCC-MR 2007)是ITER装置中构成等离子体腔室第一道密封屏障的设备或部件设计和制造的依据。本文在研究RCC-MR 2007主要内容的基础上,分析了RCC-MR 2007中1、2、3级机械设备设计相关的通用要求、材料要求、设计通则、设备性能分析要求之间的区别,同时对1、2、3级壳体、管道、箱式结构、热交换器、阀门和波纹管设计要求之间的差异进行了分析。     

Design optimization of a Class VII Flextensional Transducer

Class VII Flextensional Transducers (FTs) have been proposed as a means of overcoming the limitation of very high prestress in Class IV FTs. These transducers are made from shells shaped like dog bone and hence are also known as dog-bone shell transducers. In this work, we report design optimization of a low frequency aluminum shell Class VII FT, resonating at 2.5 kHz, using piezoelectric drive. Two and three dimensional Finite Element Modeling (FEM), with the help of a commercially available package ATILA have been used for the design optimization. Dimensional details of the base model have been adapted from previous literature. Parametric analyses have been done with respect to various aspects like type of rubber, shell height, shell material, etc. in order to optimize the design. Experimental results obtained from an initial prototype are also presented. The results match fairly well with the predicted values.     

Modified No-hair Conjecture and the Limiting Process

It is argued that the Schwarzschild black hole solution follows as a unique limit of the Brans-Dicke Class I solutions, provided the correct iterated limit is taken. Such a uniqueness is essential for the validity of a recent version of the no-hair conjecture. A non-trivial modification to this version is proposed in order to exclude Brans-Dicke Class IV solutions which appear to represent scalar hair black holes in general.     

Charged anisotropic matter with quadratic equation of state

We extend the work of Thirukkanesh and Maharaj (Class Quantum Gravity 25:235001, 2007) by considering quadratic equation of state for the matter distribution to study the general situation of a compact relativistic body. Presence of electromagnetic field and anisotropy in the pressure are also assumed. Some new classes of static spherically symmetrical models of relativistic stars are obtained. All the results given in Thirukkanesh and Maharaj (Class Quantum Gravity 25:235001, 2007) and there in can also be recovered as a particular case of our work.     

Ⅳ型弯张换能器振动辐射特性分析

本文利用等效电路支路阻抗分析方法,研究了IV型弯张换能器振动辐射特性与换能器结构之间的关系,得出一系列对换能器设计有用的结论。     

显微共聚焦拉曼光谱技术结合化学计量法鉴别静电复印纸

静电复印纸的鉴别是法庭科学物证检验中的一项重要工作。建立显微共聚焦拉曼光谱技术结合化学计量学检验、鉴别不同品牌、型号静电复印纸的分析方法,以实现对静电复印纸的无损检验和准确鉴别。收集不同品牌、不同型号的静电复印纸共计20种,利用激光波长为785 nm的半导体激光器,采集不同纸张样品的拉曼光谱数据,分析每种纸张样品中的主要特征峰及对应的物质成分;将光谱数据使用沃尔德系统聚类分析法进行分类,并采用主成分分析法评价聚类分析的鉴别结果。研究发现,不同纸张样品的主要特征峰集中在900～1 700 cm^-1范围内,分别位于714, 892, 1 092, 1 119, 1 143, 1 343, 1 385, 1 470, 1 510和1 600 cm^-1附近,主要成分为纤维素、木素和碳酸钙;各纸张样品的光谱曲线虽然相互交叠,但峰强度和峰面积存在一定差异,可利用化学计量学中的聚类分析和主成分分析对纸张样品的光谱数据进行分类鉴别。根据系统聚类分析的树状图和按计划表绘制的散点图可将20种不同品牌、不同型号的静电复印纸样品分为四类,其中第Ⅰ类中包含10份样品,...     

A test of magnetic field effects on an electron-transfer system: adiabatic or not?

Electron transfer (ET) systems in solution where the rate of transfer can be directly measured could in certain cases be expected to undergo modification by large magnetic fields. This possibility was tested on the classical manganate-permanganate system in solution. Rates were measured by NMR line broadening in significantly different magnitudes of NMR spectrometer magnetic fields. (Field throughout means a magnetic not an electric field.) Any rate changes fell within the bounds of error. This accords with the adiabatic Marcus model of such transfers, corresponding with the Robin-Day Class 2 mixed-valence interaction with a Landau–Zener transition probability of unity. Studies of the solid-state system at low temperatures have implied possibly limited electron delocalization (i.e. Robin-Day Class 1).     

Broadband flextensional transducer with major axis lengthened

The bandwidth of the Class IV flextensional transducer is narrow for its high mechanical quality factor.For improving its bandwidth performance,a flextensional transducer with major axis lengthened was proposed by the theory of multiple-mode-coupling based on the oval shell.The transducer driven by novel relaxor ferroelectric single crystal lead magnesium niobate-lead titanate(PMNT)was designed and analysed using finite element software ANSYS and a prototype of the transducer was developed.The transmitting voltage response of the transducer reaches to 136 dB with fluctuation 7.8 dB from 1.6 kHz to 16 kHz.Based on the theoretical analysis and experimental results,it proves that the flextensional transducer with major axis lengthened has a much broader bandwidth than the ClassⅣflextensional transducer combing with the advantages of low frequency and high response.     

Variational principles and spatially-homogeneous universes,including rotation

The validity of imposing spatial homogeneity on the variations in the usual action principle for Einstein's equations is studied. It is proved that with this procedure the standard and ADM Lagrangians give correct Einstein equations if and only if the space belongs to Class A of Ellis and MacCallum [1], i.e., the structure constants of the simply transitive group satisfy C _fg ^f =0. The possibility of overcoming this difficulty in the Class B spaces is examined.This work was supported in part by the United States Atomic Energy Commission under Contract Number AT 104-37-39 Project Agreement No. 125.     

无机/有机稀土配合物杂化发光材料研究进展

近年来材料的发展趋势是功能互补,性能优化。稀土配合物发光强度大、单色性好,缺点是光稳定性和热稳定性较差,因此须将其掺入一定基质中,这样所得到的有机 /无机杂化发光材料,兼备了有机、无机材料的优点。根据杂化材料中稀土配合物与基质之间作用力不同,可分为第一类杂化材料(两相间以弱键如氢键等结合)和第二类杂化材料(两相间以强键如共价键等结合)。对这两类杂化材料近年来国内外的研究情况作了综合评述,并展望了其发展趋势。     

无外接电源富集装置-手持式XRF现场分析水体中重金属

水体中重金属污染越来越受到人们的关注与重视,急需开发高效低耗、利于推广的便携式的水质检测技术,帮助地质及环境领域的工作者现场获取实验数据,对污染区域及时做出准确的水体环境评价,有助于水体污染的预防与治理工作。采用无外接电源的富集装置,在pH 4的条件下以S-930螯合树脂捕集水体中的重金属,经抽滤制得均匀薄膜样,再使用手持式XRF现场分析水体中Mn,Fe,Ni,Cu,Zn和Pb等6种重金属元素。各元素标准曲线的相关性r>0.992,方法检出限为5.8~18.6 μg·L-1,精确度基本控制在15% RSD以内。方法应用于我国东北某矿区周边采集的20余个地表/下水样品的现场分析,检测结果与实验室ICP-MS结果进行了对比：两种方法的Pb,Ni和Cu一致性良好;Zn和Mn含量高的样品,ICP-MS结果高于现场XRF结果,可能因溶液中存在细微悬浮颗粒引起,但总体趋势一致;两种方法对水质类型的总体判断结果一致。本法使用的富集和测量装置体积小、重量轻、便于携带,不使用外接电源,可在12 h内现场完成10个水体样品的采集、前处理操作、结果获取及数据处理等工作,避免实验室分析方法检测工作中存在的交通运输、测试周期长、测试成本高等问题,基本具备了在偏远地区现场分析水体中六种重金属元素、评定水质的能力,具有较好的推广应用前景。     

A Complete Analysis of Clarity (C50) Using I-SIMPA to Maintain Ideal Conditions in an Acoustic Chamber

In any closed environment considered, it can be seen that the acoustic parameters are inherently not constant over the entire area considered. In a closed environment, it is ideally preferred to maintain the acoustic parameters as constant so that there exists better quality of sound leading to better auditory perception with respect to the audience. Practically, some of the acoustic parameters like reverberation time and clarity do not strictly pertain to the pattern obtained theoretically. In this paper, simulations are carried out using I-SIMPA under different values of Sound Transmission Class (STC), source position, distribution and the chamber dimensions and provides an insight into the behaviour of these acoustic parameters and the appropriate values that have to be infused into the system to build the chamber. The acoustic environment is modelled keeping an actual closed room in mind and testing is done with respect to different values of surface absorption coefficients (practically indicated using Sound Transmission Class) and dimensions to determine ideal conditions.     

A QoS-Guanranteed Scheduling Algorithm with High Throughput for Edge Nodes of Optical Burst Switching Networks

A scheduling algorithm for the edge nodes of optical burst switching (OBS) networks is proposed to guarantee the delay re quirement of services with different CoS (Class of Service) and provide lower burst loss ratio at the same time. The performance of edge nodes based on the proposed algorithm is presented.     

Origin软件在大学物理实验教学过程中的应用

文章以A类超声波在水中的传播速度的测量和液晶光开关电光特性的研究实验为例,详细描述了Origin软件在数据处理中的应用,结果表明在大学物理实验教学中引入Origin软件是可行的.     

A feasible excitation mechanism for interstellar Class II methanol masers

A new excitation mechanism for interstellar Class II methanol masers—maser without population inversion is argued. The 107 GHz masers is taken as an example to demonstrate that our new mechanism is associated with astronomical conditions.     

On the physical meaning of the NUT parameter

Exact interpretation of the NUT parameter becomes possible when a static Schwarzchild mass is immersed in a stationary, source free electromagnetic universe. We explain this on the basis of our solution (Halilsoy and Al-Badawi in Class Quantum Grav 12:3013, 1995), which represents the non-linear superposition of the Schwarzschild solution and the generalized Bertotti–Robinson solution.     

Frequency fine-tuning in Class IV flextensional transducers

Class IV flextensional transducers (FTs) are the best-known FTs in literature. These are light-weight projectors (compared to the conventional Tonpilz designs) with capability for high power delivery at low frequencies. The resonance frequencies of this type of transducers are known to be dominantly dependent on the characteristics of the outer shell than on the driver stack. Consequently, the method of achieving fine-tuning of the transducer by modifying the characteristics of the stack, as practiced in the case of Tonpilz designs, is not very effective. This paper describes a method for fine-tuning of the frequency of a Class IV FT, which involves only a modification of a pair of small components used for coupling the stack to the transducer. The effectiveness of the method is examined by finite element modelling using the package ATILA, in the case of a 3 kHz aluminium shell transducer. Experimental results are also presented.     

Evaluating airborne sound insulation in terms of speech intelligibility

This paper reports on an evaluation of ratings of the sound insulation of simulated walls in terms of the intelligibility of speech transmitted through the walls. Subjects listened to speech modified to simulate transmission through 20 different walls with a wide range of sound insulation ratings, with constant ambient noise. The subjects' mean speech intelligibility scores were compared with various physical measures to test the success of the measures as sound insulation ratings. The standard Sound Transmission Class (STC) and Weighted Sound Reduction Index ratings were only moderately successful predictors of intelligibility scores, and eliminating the 8 dB rule from STC led to very modest improvements. Various previously established speech intelligibility measures (e.g., Articulation Index or Speech Intelligibility Index) and measures derived from them, such as the Articulation Class, were all relatively strongly related to speech intelligibility scores. In general, measures that involved arithmetic averages or summations of decibel values over frequency bands important for speech were most strongly related to intelligibility scores. The two most accurate predictors of the intelligibility of transmitted speech were an arithmetic average transmission loss over the frequencies from 200 to 2.5 kHz and the addition of a new spectrum weighting term to R(w) that included frequencies from 400 to 2.5 kHz.     

变张换能器的等效电路支路阻抗分析方法

本文提出了适用于弯张换能器的等效电路支路阻抗分析方法,归纳总结了一些描述IV型弯张换能器振动辐射的特性参量,通过支路阻抗分析方法计算这些特性参量可以进行换能器局部结构的优化设计.