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Frequency–angle two-dimensional reflection coefficient modeling based on terahertz channel measurement Correspondence

Zhaowei CHANG, Jianhua ZHANG, Pan TANG, Lei TIAN, Li YU, Guangyi LIU, Liang XIA,changzw12345@bupt.edu.cn,jhzhang@bupt.edu.cn

Frontiers of Information Technology & Electronic Engineering 2023, Volume 24, Issue 4,   Pages 626-632 doi: 10.1631/FITEE.2200290

Abstract: Terahertz (THz) channel propagation characteristics are vital for the design, evaluation, and optimization of THz communication systems. Moreover, reflection plays a significant role in channel propagation. In this correspondence, the reflection coefficients of the THz channel are researched based on extensive measurement campaigns. First, we set up the THz channel sounder from 220 to 320 GHz at incident angles ranging from 10◦ to 80◦. Based on the measured propagation loss, the reflection coefficients of five building materials, i.e., glass, tile, board, plasterboard, and aluminum alloy are calculated separately for frequencies and incident angles. It is found that the lack of THz-relative parameters leads to an inability to successfully fit the Fresnel model of nonmetallic materials to the measurement data. Thus, we propose a frequency–angle two-dimensional reflection coefficient (FARC) model by modifying the Fresnel model with the Lorenz and Drude models. The proposed model characterizes the frequency and incident angle for reflection coefficients and shows low root-mean-square error (RMSE) with the measurement data. Generally, these results are useful for modeling THz channels.

Keywords： 太赫兹通信；反射系数建模；入射角；建筑材料；菲涅耳模型    

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Expressions for Differential and Apparent Coefficients of Static Friction

Wang Weiyuan

Strategic Study of CAE 2001, Volume 3, Issue 8,   Pages 29-32

Abstract:

Recently, scientists and engineers are interested in coefficients of static friction on micro and nano scale. On macro scale, the friction force is proportional to load, the apparent coefficients of static friction are always constant and not related with the load and the contact area between the load and the substrate, which have been described as Amontons' laws. However, a lot of experiments carried out with scanning microscope, atomic force microscope and friction force microscope on micro or nano scale showed that Amontons' laws can not used successfully. On micro or nano scale, there is no general expression published in literatures to describe the relationship between the coefficients of static friction and the load. Also the published data do not compare with and discuss each other. In this paper, from the definition of differential coefficients of static friction, the expressions for differential and apparent coefficients of static friction, 〓 and 〓 for several models are deduced. Only 〓 can be measured in experiments, which can be the coefficients on micro or macro scale depending on the load on the substract, but 〓 can not be measured because the differential variables are too small to measure. In Amontons' model, 〓 equals to 〓 and both are constant. In single asperity model with load on micro or nano scale, 〓 and 〓 are not constant but propotional to P-1. In the model based on absoption layers as third bodies between two contact bodies, 〓 is a constant, 〓 is not a constant but proportional to P-1. 〓 is a constant only in high normal pressure. In the model based on constant P, 〓 and 〓 are related with F and A . Finally, the experimental data published in literatures have been discussed based on the novelly deduced expressions.

Keywords： differential coefficients of static friction     coefficients of static friction on micro or nano scale     apparent coefficients of static friction     coefficients of static friction on macro scale    

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A algorithm for binocular stereo matching in the presence of specular reflections

Lu Sijun,Tang Zhenmin,Guo Longyuan,Lu Ali

Strategic Study of CAE 2010, Volume 12, Issue 1,   Pages 56-60

Abstract:

Traditional stereo correspondence algorithms rely heavily on the Lambertian model of diffuse reflectance. While this diffuse assumption is generally valid for most part of an image, processing of regions that contain specular reflections can result in severe matching errors. In this paper, we address the problem of binocular stereo dense matching in the presence of specular reflections by introducing a novel correspondence measurement which is robust to the specular reflections. Accurate depth can be estimated for both diffuse and specular regions. Unlike the previous works which seek to eliminate or avoid specular reflections using image preprocessing or multibaseline stereo, our approach works in its presence. Experiments demonstrate the effectiveness and robustness of our approach.

Keywords： stereo matching     diffuse reflection     specular reflection     chromaticity    

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SH-Mode Seismic-Reflection Imaging of Earthfill Dams Article

Edward W. Woolery

Engineering 2018, Volume 4, Issue 5,   Pages 694-701 doi: 10.1016/j.eng.2018.08.009

Abstract:

Assessing subsurface characteristics and imaging geologic features (e.g., faults, cavities, low-velocity layers, etc.) are typical problems in near-surface geophysics. These questions often have adverse geotechnical engineering implications, and can be especially acute when associated with high-hazard structures such as large earthen flood-control dams. Dam-related issues are becoming more frequent in the United States, because a large part of this major infrastructure was designed and constructed in the early- to mid-twentieth century; these dams are thus passing into the latter stages of their design life, where minute flaws that were overlooked or thought to be insignificant in design/construction are now proving problematic. The high-hydraulic heads associated with these structures can quicken degradation of weak areas and compromise long-term integrity. Addressing dam-related problems solely with traditional invasive drilling techniques is often inadequate (i.e., lack of lateral resolution) and/or economically exorbitant at this scale. However, strategic geotechnical drilling integrated with the broad utility of near-surface geophysics, particularly the horizontally polarized shear-wave (SH-mode) seismic-reflection technique for imaging the internal structural detail and geological foundation conditions of earthfill embankment dams can cost-effectively improve the overall subsurface definition needed for remedial engineering. Demonstrative evidence for this supposition is provided in the form of SH-wave seismic-reflection imaging of in situ and engineered as-built components of flood-control embankment dams at two example sites in the central United States.

Keywords： Geophysics     Seismic reflection     Shear-wave     Near-surface     Dam safety    

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An intuitive general rank-based correlation coefficient Research Articles

Divya PANDOVE, Shivani GOEL, Rinkle RANI

Frontiers of Information Technology & Electronic Engineering 2018, Volume 19, Issue 6,   Pages 699-711 doi: 10.1631/FITEE.1601549

Abstract: Correlation analysis is an effective mechanism for studying patterns in data and making predictions. Many interesting discoveries have been made by formulating correlations in seemingly unrelated data. We propose an algorithm to quantify the theory of correlations and to give an intuitive, more accurate correlation coefficient. We propose a predictive metric to calculate correlations between paired values, known as the general rank-based correlation coefficient. It fulfills the five basic criteria of a predictive metric: independence from sample size, value between 1 and 1, measuring the degree of monotonicity, insensitivity to outliers, and intuitive demonstration. Furthermore, the metric has been validated by performing experiments using a real-time dataset and random number simulations. Mathematical derivations of the proposed equations have also been provided. We have compared it to Spearman’s rank correlation coefficient. The comparison results show that the proposed metric fares better than the existing metric on all the predictive metric criteria.

Keywords： General rank-based correlation coefficient     Multivariate analysis     Predictive metric     Spearman’s rank correlation coefficient    

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Optimal design of a large dual-polarization microstrip reflectarray with China-coverage patterns for satellite communications Research Articles

Gang ZHAO, Yong-chang JIAO, Guan-tao CHEN

Frontiers of Information Technology & Electronic Engineering 2020, Volume 21, Issue 1,   Pages 159-173 doi: 10.1631/FITEE.1900496

Abstract: A large dual-polarization microstrip reflectarray with China-coverage patterns in two operating bands is designed. To sufficiently compensate for the spatial phase delay differences in two operating bands separately, a three-layer rectangular patch element is addressed, which is suitable for the large dual-polarization reflectarray. Due to the complexly shaped areas and high gain requirements, there are more than 25 000 elements in the reflectarray, making it difficult to design, due to more than 150 000 optimization variables. First, the discrete fast Fourier transform (DFFT) and the inverse DFFT are used to establish a one-to-one relationship between the aperture distribution and the far field, which lays a foundation for optimizing the shaped-beam reflectarray. The intersection approach, based on the alternating projection, is used to obtain the desired reflection phases of all the elements at some sample frequencies, and a new method for producing a suitable initial solution is proposed to avoid undesired local minima. To validate the design method, a dual-polarization shaped-beam reflectarray with 7569 elements is fabricated and measured. The measurement results are in reasonable agreement with the simulation ones. Then, for the large broadband reflectarray with the minimum differential spatial phase delays in the operating band, an approach for determining the optimal position of the feed is discussed. To simultaneously find optimal dimensions of each element in two orthogonal directions, we establish a new optimization model, which is solved by the regular polyhedron method. Finally, a dual-band dual-polarization microstrip reflectarray with 25 305 elements is designed to cover the continent of China. Simulation results show that patterns of the reflectarray meet the China-coverage requirements in two operating bands, and that the proposed optimization method for designing large reflectarrays with complexly shaped patterns is reliable and efficient.

Keywords： Reflectarray     Dual-polarization     Shaped beam     Phase-only synthesis    

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The stability safety factor calibration based on the reliability index

Tong Xiaolong,Fang Zhi

Strategic Study of CAE 2012, Volume 14, Issue 11,   Pages 44-48

Abstract:

When the bridge structure stability safety factor of the first type is 4, the research that whether the structure reliability index will reach target reliability index under the more-likely-to-happen collapse situation of the second type is necessary. The stability calculations of the first and the second type are made respectively for single layer and single span rigid frame bridge. Based on the critical load obtained from the stability calculation of the first type, the stability safety factor of the first type is taken as 4, and the first order reliability method is used to program and calculate the reliability index. Then, the load effect under the stability reliability index calculation of the first type and the critical load of the second type are employed to calculate the reliability index of the second type. The evaluation of structure stability safety factor is discussed according to reliability index. Based on the discussion above, parameter analysis of the stable critical loads of two types is made, and the influence of critical load change on reliability index is researched. The result shows that stability analysis should identify collapse state; when the stability safety index of the first type is 4, and the structure has the collapse of the second type, the reliability index cannot ensure to reach the target reliability index under some situations.

Keywords： stability safety factor     reliability index     rigid frame bridge    

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Properties of photosynthesis and spectral reflectance in leaves of maize under the low and variable water conditions

Sun Li,Su Gengqiang,Liu Yanmei,Zhao Yanyan and Shi Gangrong

Strategic Study of CAE 2012, Volume 14, Issue 3,   Pages 70-75

Abstract:

The present study was carried out to examine the effects of low and variable water conditions on plant biomass, root to shoot ratio, chlorophyll fluorescence, gas exchange and spectral features in leaves of maize (Zea mays cv. Suyu 19) by pot experiment. The results showed that continuing drought led to an inhibition of plant growth, increase of root to shoot ratio, and inhibition of photosynthesis through stomatal and/or nonstomatal limitations. The mSR705, chlNDI and REP were also significantly reduced by continuing drought compared to the controls, whereas SIPI was unaffected. Under the low and variable water conditions, plant growth was inhibited, however, the root to shoot ratio, chlorophyll fluorescence, gas exchange and spectral properties were similar to the controls. The results indicated that the maintenance of biomass allocation, photosynthesis and spectral reflectance might be an important mechanism for maize to adapt the low and variable water conditions.

Keywords： Maize     low and variable water conditions     chlorophyll fluorescence     gas exchange     spectral reflectance    

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The Method and Formula for Stability Factor of Slope with State of Soil Original Stress

Wang Guoti

Strategic Study of CAE 2006, Volume 8, Issue 12,   Pages 80-84

Abstract:

The methods for analysis of stability of slope are usually considered, developed and improved along the line of finite slice method. But the safety factor of stability is facing challenge in engineering application. Because of the state of original stress in soil is ignored and disfigurement of finite slice method is in existence at all time. In different conditions of soil consolidation, K0, the lateral stress coefficient of soil state, has influenced the property of soil and excavation of slope. In this paper, in consideration of the state of soil original stress, the calculating formula for safety factor have been given with applying Coulomb's equation for shear strength of soil and Mohr - Coulomb rule. There are many examples of safety factor using the formula of this paper, which have been calculated and compared with finite slice methods selected from reference literatures. The formula have showed their clear concept, simple calculation and dependable result. They can be used in engineering.

Keywords： ateral stress coefficient K0     state of original stress     formula of safety factor of stability    

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Thermodynamic Analysis of Thermoelectric Process and Measurement for Seebeck Coefficient of Thermoelectric Material

Jia Lei,Hu Peng,Chen Zeshao

Strategic Study of CAE 2005, Volume 7, Issue 12,   Pages 31-34

Abstract:

A basic model of semiconductor thermoelectric generator is constituted. Based on the steady conduction equation, thermodynamic process has been analyzed. Temperature function, output power and generating efficiency of p and n semiconductor are obtained. The Seebeck coefficient S of a kind of Bi-Te-Sb-Se thermoelectric material at low temperature has been experimentally researched. Based on the experiment, the function between S and T of this material has been expressed. The conclusion indicates that this kind of thermoelectric material is unsuitable for power generation at low temperature, and only the enhancement of production technology or appearance of new production method can improve the electrical power generation performance.

Keywords： semiconductor     thermoelectric     thermodynamic process     Seebeck coefficient    

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Development of Simulation Technologies and Researches of Modeling Theory for Power Plant in China

Lü Chongde,Fan Yongsheng,Cai Ruizhong

Strategic Study of CAE 1999, Volume 1, Issue 1,   Pages 99-103

Abstract:

In this paper the development of simulation technologies and modeling theory of the fossil power generating unit in China is discussed and analysed. Authors described developing process of the fossil power simulators from scientific researches to achieving the most quantity in the world. While the information of electric power simulators distributed over the world is given. The key technologies——modeling theory and method of the thermal system simulation are summarized. Authors expounded the lumped parameter model, distributed parameter model, dynamic revised model of high precision lumped parameter and other model. These model equations are applied various simulated objects and different simulation precision.

Keywords： system simulation     modeling     electric power    

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The Military Large-scale Complex System's Modeling and Simulation Based on Agent

Li Honggang,Lü Hui,Liu Xingtang

Strategic Study of CAE 2004, Volume 6, Issue 8,   Pages 40-44

Abstract:

First of all this paper introduces the composition and the principle of agent and makes thorough analysis of modeling process of military large-scale complex system, then presents the modeling and simulating result of the military large-scale complex system, and makes an analysis of the simulating result.

Keywords： complex system     agent     modeling and simulation    

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Optical Problems in Imaging Optical Engineering

Pan Junhua

Strategic Study of CAE 2000, Volume 2, Issue 3,   Pages 32-35

Abstract:

In this paper the critical area using imaging optics is discussed, i. e. the ground based astronomical telescopes, observing systems from the space to the Earth and the projecting lithographic systems. According to the trend of technical progress, it is unavoidable to use reflective optical systems, and consequently as-pherical surfaces. For optical system design, the main problem is how to construct an effective reflecting system which may be optimized by the optical CAD. The need of unobscurating entrance pupil leads using off-axis reflecting system and tilted mirror system. The key problem in fabrication is to make high accuracy, large relative aperture, high-order, large asphericity/aspherical slope and section symmetric surfaces. The null method is the principal way for testing aspheric surfaces up to now. The design of compensator for highorder, off-axis aspheric mirrors is worth studying yet.

Keywords： imaging optics     aspheric mirror     optical design     optical fabrication and testing    

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Fuzzy Modeling Theory on Production Scheduling： A Survey

Zhang Hong,Li qiqiang,Guo qingqiang,Zhang Peng,Gao Yuan

Strategic Study of CAE 2005, Volume 7, Issue 12,   Pages 92-102

Abstract:

A brief survey on classical modeling theory of production scheduling is presented in this paper. With the combination of fuzzy mathematical theory and classical modeling or intelligent methods, a brief survey on fuzzy modeling theory is also presented. Some perspective viewpoints are pointed out in the last section of the paper.

Keywords： production scheduling     fuzzy mathematics     fuzzy modeling    

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Study on the Modern Building Models & Optimum Technique——Application of Water Saving System for Well Irrigation Rice in Sanjiang Plain

Fu Qiang

Strategic Study of CAE 2002, Volume 4, Issue 6,   Pages 44-55

Abstract:

The author applies covertly and macroscopically the SPAC theory model to the water saving system of well irrigation rice in Sanjiang Plain. Several sub-systems have been taken as a whole large system, such as groundwater, machine well, sunning water pool, channel, field, environment and so on. Through applying modern building models and optimization technique, the author analyzes the mechanism and theory of each subsystem, some mathematical models about groundwater, sunning water pool, channel, water production function, water requirement and available rainfall have been built. At last, through designing the typical demonstration area, the author combines several water-saving techniques into a whole system. Thus, the goal of raising water temperature 5～15℃ , saving water 17.1% and increasing yield 700 ～1 000 kg/hm2 canbe reached.

Keywords： building models     optimization     Sanjiang Plain     well irrigation rice     system    

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Title Author Date Type Operation

Frequency–angle two-dimensional reflection coefficient modeling based on terahertz channel measurement

Zhaowei CHANG, Jianhua ZHANG, Pan TANG, Lei TIAN, Li YU, Guangyi LIU, Liang XIA,changzw12345@bupt.edu.cn,jhzhang@bupt.edu.cn

Journal Article

Expressions for Differential and Apparent Coefficients of Static Friction

Wang Weiyuan

Journal Article

A algorithm for binocular stereo matching in the presence of specular reflections

Lu Sijun,Tang Zhenmin,Guo Longyuan,Lu Ali

Journal Article

SH-Mode Seismic-Reflection Imaging of Earthfill Dams

Edward W. Woolery

Journal Article

An intuitive general rank-based correlation coefficient

Divya PANDOVE, Shivani GOEL, Rinkle RANI

Journal Article

Optimal design of a large dual-polarization microstrip reflectarray with China-coverage patterns for satellite communications

Gang ZHAO, Yong-chang JIAO, Guan-tao CHEN

Journal Article

The stability safety factor calibration based on the reliability index

Tong Xiaolong,Fang Zhi

Journal Article

Properties of photosynthesis and spectral reflectance in leaves of maize under the low and variable water conditions

Sun Li,Su Gengqiang,Liu Yanmei,Zhao Yanyan and Shi Gangrong

Journal Article

The Method and Formula for Stability Factor of Slope with State of Soil Original Stress

Wang Guoti

Journal Article

Thermodynamic Analysis of Thermoelectric Process and Measurement for Seebeck Coefficient of Thermoelectric Material

Jia Lei,Hu Peng,Chen Zeshao

Journal Article

Development of Simulation Technologies and Researches of Modeling Theory for Power Plant in China

Lü Chongde,Fan Yongsheng,Cai Ruizhong

Journal Article

The Military Large-scale Complex System's Modeling and Simulation Based on Agent

Li Honggang,Lü Hui,Liu Xingtang

Journal Article

Optical Problems in Imaging Optical Engineering

Pan Junhua

Journal Article

Fuzzy Modeling Theory on Production Scheduling： A Survey

Zhang Hong,Li qiqiang,Guo qingqiang,Zhang Peng,Gao Yuan

Journal Article

Study on the Modern Building Models & Optimum Technique——Application of Water Saving System for Well Irrigation Rice in Sanjiang Plain

Fu Qiang

Journal Article