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A two-stage amplifier of laser eavesdropping model based on waveguide fiber taper

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Defence Technology（防务技术） 2019年第1期15卷 95-97页

作者： Mei-ting Wang Yan Zhu Yi-ning Mu School of Science Changchun University of Science and Technology

In order to improve ability of amplification about optical arrival angle in laser eavesdropping system, and enhance receiving field of view (FOV) of laser eavesdropping system, this paper presents a new multistage amplifier laser eavesdropping model based on waveguide fiber taper. First of all, taking about four-quadrant (4QD) laser eavesdropping model as an example, from the theoretical view, analyses factors that, currently, laser eavesdropping system face many restrictive factors during practical applications. Besides, from the receiving FOV and ability of amplification about arrival angle of incoming optical axis angles, systematically analyses advantages of multi-stage amplifier model. What’s more,through constructing laser eavesdropping test platform, we demonstrate Signal to Noise Ratio(SNR) of two stage amplification model is eventually promoted to 6-10 dB compared with one amplifying model,especially in low and high audio level, the advantages is more obvious.

关键词： Laser eavesdropping Waveguide fiber taper 4QD

Analysis and design of the taper in metal-grating periodic slow-wave structures for rectangular Cerenkov masers

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Chinese Physics B 2012年第5期21卷 662-668页

作者：陈晔赵鼎王勇舒雯 Key Laboratory of High Power Microwave Sources and Technologies Institute of ElectronicsChinese Academy of Sciences Graduate University of Chinese Academy of Sciences

The hybrid-mode dispersion equation of the metal-grating periodic slow-wave structure for a rectangular Cerenkov maser is derived by using the Borgnis function and field-matching methods.An equivalent-circuit model for the taper of the groove depth that matches the smooth waveguide to the metal-grating structure is proposed.By using the equivalentcircuit method,as well as the Ansoft high frequency structure simulator（HFSS） code,an appropriate electromagnetic mode for beam-wave interaction is selected and the equivalent-circuit analysis on the taper is given.The calculated results show that a cumulative reflection coefficient of 0.025 for the beam-wave interaction structure at a working frequency of 78.1 GHz can be reached by designing the exponential taper with a TE z10 rectangular waveguide mode as the input and the desired TE x10 mode as the output.It is worth pointing out that by using the equivalent-circuit method,the complex field-matching problems from the traditional field-theory method for taper design can be avoided,so the taper analysis process is markedly simplified.

关键词： rectangular Cerenkov maser Borgnis function method equivalent-circuit method HFSS taper

Calculation of taper Rolling Time in Plan View Pattern Control Process

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Journal of Iron and Steel Research(International) 2006年第5期13卷 1-3页

作者： JIAO Zhi-jie HU Xian-lei ZHAO Zhong LIU Xiang-hua WANG Guo-dong State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

The forward slip model with adhesion was used to derive the formula of calculating taper rolling time. The relation between the rolling time and the taper length and the relation between the rolling time and the taper thickness can be obtained. The numerical solution for this formula was used on site. According to the simulation result, the roll gap value should be changed linearly with rolling time.

关键词： plan view pattern control forward slip model taper time calculation

Refractive index and temperature sensor based on cleaved taper and spherical structure

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Optoelectronics Letters 2020年第3期16卷 171-175页

作者：仲怡美童峥嵘宋殿友张卫华秦娟高文林 Tianjin Key Laboratory of Film Electronic and Communication Devices Engineering Research Center of Optoelectronic Devices and Communication TechnologyMinistry of EducationSchool of Electrical and Electronic EngineeringTianjin University of TechnologyTianjin 300384China

An in-line Mach-Zehnder interferometer(MZI) for simultaneous measurement of temperature and refractive index(RI) is proposed and demonstrated. The sensor is composed of cleaved taper, single-mode fiber(SMF) and spherical structure. Using precision device to measure the position of waist, the cleaved taper structure is obtained by cutting the taper structure. The sensitivities of the temperature are 0.052 nm/℃ and 0.037 nm/℃ in the temperature range of 25-70 ℃, respectively. The RI sensitivities are-56.59 nm/RIU and-43.53 nm/RIU in the RI range of 1.335-1.38, respectively. This sensor has many advantages such as compact structure and good stability.

关键词： taper interferometer fiber

Influence of Gravity and taper on the Vibration of a Standing Column

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Advances in Applied Mathematics and Mechanics 2012年第4期4卷 483-495页

作者： C.Y.Wang Departments of Mathematics and Mechanical Engineering Michigan State UniversityEast LansingMI 48824USA

The stability and natural vibration of a standing tapered vertical column under its own weight are studied.Exact stability criteria are found for the pointy column and numerical stability boundaries are determined for the blunt tipped column.For vibrations we use an accurate,efficient initial value numerical method for the first three frequencies.Four kinds of columns with linear taper are considered.Both the taper and the cross section shape of the column have large influences on the vibration frequencies.It is found that gravity decreases the frequency while the degree of taper may increase or decrease frequency.Vibrations may occur in two different planes.

关键词： Vibration column taper weight

Theoretical and experimental research on influence of rotor taper on performance of cone-shape helical pumps

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High Technology Letters 2019年第2期25卷 174-181页

作者：赵建华 Gao Dianrong Liu Shichang Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University

The structure of a rotor has full impact on the performance of cone-shaped helical pumps. Numerical simulation and experimental tests are applied to get pressure, velocity and flow of a cone-shaped helical pump, and explores flow condition of blood in artificial blood pump. Rotors with four different tapers of artificial pump are designed. The flow condition of blood at the entrance, near the front diffuser, near the rotor, near the rear diffuser and at the exit, the pressure difference between entrance and exit and flow of artificial blood pump with different taper rotors are simulated, and then the influence rules of rotor taper on the performance of cone-shaped helical pump are revealed. In order to verify the correctness of theoretical analysis, rotors with three different tapers are manufactured, physical model of artificial blood pump are built, and then the actual lift and flow of blood pump with different rotors are measured respectively. The results show that taper of rotor increases, the circumfluence of blood near the front and rear diffuser decreases, the blood flows more smoothly, the energy consumption is less, and then the guide role of blade is greater. The blood at the exit of blood pump flows along the axial direction steadily. As taper of rotor increases, the pressure difference between the entrance and exit and the flow of blood pump increase subsequently. The flow condition of blood and performance of blood pump with No.3 rotor are the best. The proposed research analyzes the influence of rotor taper on performance of blood pump quantitatively, and provides the theoretical reference for the design and improving of cone-shaped helical pump.

关键词： cone-shaped helical pump rotor taper circumfluence flow condition energy consumption

Efficient adiabatic silicon-on-insulator waveguide taper

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Photonics Research 2014年第3期2卷 S0041-S0044页

作者： Yunfei Fu Tong Ye Weijie Tang Tao Chu State Key Laboratory of Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

A silicon-on-insulator-based adiabatic waveguide taper with a high coupling efficiency and small footprint is presented.The taper was designed to reduce the incidence of mode conversion to higher-order and radiation modes inside the waveguide.In connecting a 0.5-μm-wide output waveguide and a 12-μm-wide input waveguide of a grating coupler,a compact 120-μm-long taper was demonstrated,achieving a transmission of 98.3%.Previously,this transmission level could only be achieved using a conventional linear taper with a length of more than 300μm.

关键词： waveguide taper adiabatic

Reduction Rate of Dragload and Downdrag of Piles by taper Angles

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Transactions of Tianjin University 2016年第5期22卷 434-440页

作者：孔纲强周立朵彭怀风顾红伟 Key Laboratory of Geomechanics and Embankment Engineering(Hohai University) Ministry of Education Nanjing 210098 China Jiangsu Province Communications Planning and Design Institute Limited Company Nanjing 210014 China

taper angle is one of the effective methods to reduce the dragload and downdrag of piles under the surcharge load. The model tests on the tapered pile and uniform cross-section pile embedded in sand were carried out under the surcharge load. The values of dragload and downdrag of piles versus the surcharge loads were measured. Based on the concentric cylinder shearing theory, a simplified theoretical model for calculating the dragload and downdrag of tapered piles with small taper angles under the surcharge load was proposed considering the angle effect. The correctness of the developed theoretical model was validated through comparing with the model test results obtained in this study and previous literature. Then the parametric studies of the taper angle, surcharge, strength and modulus of soil were discussed. It is shown that the tapered pile with the taper angle of 3° can reduce approximately 65% of the maximum dragload value and 30% of the downdrag value compared with a uniform cross-section pile. The value of downdrag can be decreased by approximately 50% compared with a uniform crosssection pile in the same average pile diameter.

关键词： pile foundation taper angle dragload downdrag model test theoretical analysis

Predicting the upper stem diameters and volume of a tropical dominant tree species

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Journal of Forestry Research 2022年第6期33卷 1725-1737页

作者： Sunita Ulak Keshav Ghimire Rabindra Gautam Shes Kanta Bhandari Krishna Prasad Poudel Yajna Prasad Timilsina Dhirendra Pradhan Thakur Subedi Forest Research and Training Centre KathmanduNepal Institute of Forestry Tribhuvan UniversityKathmanduNepal School of Biological Sciences The University of Western AustraliaPerthAustralia Department of Forestry Mississippi State UniversityMississippi StatePO Box 9681Starkville 39762USA

Predicting upper stem diameters and individual tree volumes is important for product quantification and can provide important information for the sustainable management of forests of important commercial tree species(Shorea robusta)in Nepal.The aim of this study was to develop a taper equation for S.robusta.Fifty-four trees were selected and felled in the southern low land of Nepal.A mixed effect modelling approach was used to evaluate 17 different taper functions.‘Leave-one-out cross-validation'was used to validate the fitted taper functions.The variable exponent taper function best fitted our data and described more than 99%of the variation in upper stem diameters.Results also showed significant effects of stand density on tree taper.Individual tree volume prediction using the local volume model developed in this study was more accurate compared to the volume predicted through the taper function and existing volume model.The taper function developed in this study provides the benefit of predicting upper stem diameter and can be used for predicting volume to any merchantable height of individual trees.It will have implications in estimates of volume,biomass,and carbon and thus may be a potential supporting tool in carbon trade and revenue generation.

关键词： Mixed-model approach Shorea robusta taper Volume Nepal