Kun Cai

China Meteorological Administration

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Shenshen Li

Shandong University

Yang Liu

Henan University

Yin Long

The University of Tokyo

Qiang Ge

Henan University

Chao Yu

State Key Laboratory of Remote Sensing Science

Yidan Si

China Meteorological Administration

Hunglin Chen

Shanghai Huali Microelectronics (China)

Yi Liao

University of Electronic Science and Technology of China

Kai Wang

Qingdao University

Liangfu Chen

State Key Laboratory of Remote Sensing Science

Cooperative Institutions

Chinese Academy of Sciences

Henan University

University of Electronic Science and Technology of China

State Key Laboratory of Remote Sensing Science

Aerospace Information Research Institute

Shanghai Huali Microelectronics (China)

University of Chinese Academy of Sciences

Institute of Remote Sensing and Digital Earth

Tsinghua University

Shanghai Jiao Tong University

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Research on the Temporal and Spatial Distribution Characteristics of Thermal Anomalies in Henan Province from 2008 to 2019

E3S Web of Conferences (2021)

Qiang Ge Wenju Shen Shenshen Li Kun Cai

Using MODIS standard products, the temporal and spatial distribution characteristics of thermal anomalies in Henan Province in the past 12 years (2008~2019) were studied. The results found that in terms of spatial distribution, thermal anomalies were mostly concentrated in Luohe, Zhumadian, Pingdingshan, Puyang, and Shangqiu. The number of areas under the jurisdiction of Anyang, Hebi, Nanyang and Xinyang is relatively high. On the inter-annual trend, the number of thermal anomalies continued to increase from 2009 to 2013, with an average annual growth rate of 28.3%, and a continuous decline from 2013 to 2018. The decline rate was 18.4%, during which the number reached a peak of 5,843 in 2013. In terms of seasonal changes, the number of summer thermal anomalies is the largest, at 25,361, and thermal anomalies of summer are mostly concentrated in most areas of Zhumadian, Pingdingshan, Puyang and Shangqiu; the number of thermal anomalies in winter is the least, 3974, which are relatively mostly distributed in the mountainous areas of Nanyang and Xinyang. This study helps to understand the forest fires in typical areas in Henan Province, as well as heat caused by straw burning, industrial emissions, etc. Thermal anomalies changes provide technical support for regional disaster prevention and environmental monitoring.

10.1051/e3sconf/202125203026

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Equivalent Circuit of Normal Mode Helical Antennas Using Frequency-Independent Lumped Elements

IEEE Transactions on Antennas and Propagation (2014)

Yi Liao Kun Cai T.H. Hubing Xiaobing Wang

An equivalent circuit consisting of eight frequency independent lumped elements is derived for center-driven normal mode helical antennas. The equivalent circuit is composed of two parts; a five-element circuit representing the wire antenna and a three-element circuit for the helical turns. Comparison of the calculated input impedance of the equivalent circuit with full-wave simulations demonstrates reasonable agreement over a broad frequency range that includes the first resonant frequency, where the antenna usually operates. Application of the equivalent circuit does not require an EM solver and it is readily implemented in circuit simulators.

Electrical element

RLC circuit

Center frequency

Helical antenna

10.1109/tap.2014.2352360

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Citations (12)

Compilation and Application of Multifunctional Lucas-Tooth Intensity Correction Software in EDXRF Spectrometer

Chinese Journal of Spectroscopy Laboratory (1997)

Kun Cai

In this paper,a multminctional lucas-tooth intensity correction software has been compiled. Thesoftware can discriminate effect of matrix correction accuratny and sharply. Then if has data processing function of multiple linear resression and internal standard mode. Analytical results were satisfied

Intensity

Mode (computer interface)

Matrix (chemical analysis)

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Pattern-centric yield management approach with machine learning to detect and track defects with full chip coverage

Yu Zhang Shirui Yu Jiaqi Liu Renyang Meng Yin Long

The importance of pattern-based defect study has grown with more complex processes in advanced semiconductor manufacturing. The pattern is the heart of the DPTCO Design Process Technology Co-Optimization approach. But the definition of pattern has been limited by the design rules that can be setup by an individual. Moreover, the huge volume of data points generated by any DRC Design Rule Check type of search forces user to sort and filter out most of them and keep only a manageable count. This effectively reduces the sample space of pattern-based learning. In this work we have employed a new approach of PCYM Pattern Centric Yield Manager where the high count of unique patterns and all its instances in full chip design is retained. It is a fundamental pillar of computational system for semiconductor fabrication where pattern-centric learning can be deployed to study any related process.

Semiconductor device fabrication

Sample (material)

10.1117/12.2583454

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Citations (2)

Generalized RCS and Near-Field Electromagnetical Scattering Modeling

Kun Cai

A definition of generalized radar scatter section(RCS) which was independent of antenna was presented based on the superposition principle of electromagnetic field in this paper.Besides the vertical and horizontal polarization,the symmetric polarization was supposed to be a third near-field polarization scattering characteristic,and more near-field polarized RCS of metal slab were calculated.According to the generalized RCS definition,a more efficient method that was decompose-compose method was given out,for which the incident field was decomposed into inhomogeneous spherical wave which radiated by electric or magnetic dipole antenna,all of the dipole antenna's scattering were composed as the final received field.The near field of a metal slab was computed by antenna pattern approximation and the decompose-compose method.The results proved the necessity of decompose-compose method in near-field case.

Radar cross-section

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Evaluating the Performance of Ozone Products Derived from CrIS/NOAA20, AIRS/Aqua and ERA5 Reanalysis in the Polar Regions in 2020 Using Ground-Based Observations

Remote Sensing (2021)

Hongmei Wang Yapeng Wang Kun Cai Songyan Zhu Xinxin Zhang

Quantifying spatiotemporal polar ozone changes can promote our understanding of global stratospheric ozone depletion, polar ozone-related chemical processes, and atmospheric dynamics. By means of ground-level measurements, satellite observations, and re-analyzed meteorology, the global spatial and temporal distribution characteristics of the total column ozone (TCO) and ozone profile can be quantitatively described. In this study, we evaluated the ozone datasets from CrIS/NOAA20, AIRS/Aqua, and ERA5/ECWMF for their performance in polar regions in 2020, along with the in situ observations of the Dobson, Brewer, and ozonesonde instruments, which are regarded as benchmarks. The results showed that the ERA5 reanalysis ozone field had good consistency with the ground observations (R > 0.95) and indicated whether the TCO or ozone profile was less affected by the site location. In contrast, both CrIS and AIRS could capture the ozone loss process resulting from the Antarctic/Arctic ozone hole at a monthly scale, but their ability to characterize the Arctic ozone hole was weaker than in the Antarctic. Specifically, the TCO values derived from AIRS were apparently higher in March 2020 than those of ERA5, which made it difficult to assess the area and depth of the ozone hole during this period. Moreover, the pattern of CrIS TCO was abnormal and tended to deviate from the pattern that characterized ERA5 and AIRS at the Alert site during the Arctic ozone loss process in 2020, which demonstrates that CrIS ozone products have limited applicability at this ground site. Furthermore, the validation of the ozone profile shows that AIRS and CrIS do not have good vertical representation in the polar regions and are not able to characterize the location and depth of ozone depletion. Overall, the results reveal the shortcomings of the ozone profiles derived from AIRS and CrIS observations and the reliability of the ERA5 reanalysis ozone field in polar applications. A more suitable prior method and detection sensitivity improvement on CrIS and AIRS ozone products would improve their reliability and applicability in polar regions.

Ozone Depletion

10.3390/rs13214375

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Citations (12)

Comparisons of the vertical distributions of aerosols in the CALIPSO and GEOS-Chem datasets in China

Atmospheric Environment X (2019)

Shenshen Li Luo Zhang Kun Cai Wei Ge Xueying Zhang

In this study, we compared the aerosol profiles derived from the Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) over China with those simulated by the Global 3-D Atmospheric Chemical Transport model (GEOS-Chem) for the period of 2007–2014. Multiple steps were implemented in the data analysis. First, we validated CALIPSO and GEOS-Chem aerosol optical depth (AOD) using Moderate Resolution Imaging Spectroradiometer (MODIS) products, both CALIPSO and GEOS-Chem AOD were found to 30%∼50% underestimations in eastern China and 60%∼80% underestimations in western China. Second, MODIS AOD was introduced to normalize the aerosol extinction coefficient (AEC) of both CALIPSO and GEOS-Chem in each 1-km layer below 10 km to achieve a uniform comparison. Linear regression analysis between the normalized CALIPSO and GEOS-Chem AECs yielded better correlation coefficients and lower mean relative differences than the direct comparisons from the original data. Finally, we investigated the vertical distributions of aerosol components over the North, South, Northwest and Tibet regions of China. Our findings are summarized based on different aerosol components as the following. Dust aerosols: The percentages of CALIPSO polluted dust to total dust in the North and South regions (50%∼68% in different seasons) are higher than those in the Northwest and Tibet regions (25%∼45%). Thus, the polluted dust classification significantly affects our comparisons in the North and South. For CALIPSO pure dust, its concentrations in the higher layers are larger than those of GEOS-Chem. Continental/sulfate, nitrate, and ammonium (SNA) aerosols: The percentages of CALIPSO continental aerosols to total aerosols are almost negligible throughout the four regions (<10%). Even including the polluted dust in the continental aerosol, their combined contributions remain ∼10% lower than GEOS-Chem SNA. Thus, we found that the current CALIPSO aerosol classification scheme is limited in the detection of anthropogenic aerosols in China. Soot aerosols: The GEOS-Chem soot aerosol values are a factor of 2–4 times lower than those of CALIPSO. The omission of small agricultural field burnings in the GEOS-Chem emission inventory might have resulted in the soot aerosol underestimations.

Chemical Transport Model

Moderate-resolution imaging spectroradiometer

Spectroradiometer

10.1016/j.aeaoa.2019.100036

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Citations (7)

Energy-Efficient Resource Allocation for Uplink Multi-User MIMO SC-FDMA Systems

2021 IEEE 21st International Conference on Communication Technology (ICCT) (2021)

Zhengguang Zheng Liyan Lin Yuyi Wang Fangzheng Wei Yun Zhang

In this paper, joint user pairing and resource allocation is investigated for improving energy efficiency of multiuser multiple-input-multiple-output (MU-MIMO) single-carrier frequency division multiple access (SC-FDMA) systems. We first formulate an optimization problem to maximize energy efficiency with the maximum transmit power constraint and restrictions of minimum rate requirements from multiple users. To reduce computational complexity, we divide the joint optimization problem into two subproblems: energy efficient power allocation and joint user pairing and resource block allocation. For these subproblems, we develop a suboptimal algorithm with low implementation complexity. Simulation results demonstrate that the proposed scheme can achieve significant energy efficiency gain compares with conventional schemes.

Transmitter power output

Frequency-division multiple access

Resource Management

10.1109/icct52962.2021.9657843

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Pattern Centric Machine Learning Approach to Uncover Process Defects During Wafer Inspection and Review

Yu Zhang Shirui Yu Jiaqi Liu Renyang Meng Yin Long

The adoption of advanced reticle enhancement techniques has allowed patterning of smallest features in semiconductor manufacturing. Though the multitude the wafer processes have created a challenge for the existing modeling techniques even in the DUV (Deep Ultraviolet) patterning. Individual process owners strive to optimize their modules based on the data that is available within their purview. The co-ownership of chip yield is now driving the design process technology co-optimization. There has been a learning that layout pattern can serve as a common index to capture the response functions from multiple wafer processes [1], [2]. This requires identification of consequential patterns in the full chip layout and preserving this comprehensive design information throughout the fabrication life cycle. The big data thus collected at every sequential process step enables Pattern Centric Machine Learning that can be utilized in the optimization of each process [3], [4]. In this work we report a use case where PCML approach was utilized in uncovering the process defects by feeding in the process control systems. This approach enabled detection of new pattern defects with optical wafer inspection that is normally used for process monitoring.

Reticle

Semiconductor device fabrication

Wafer fabrication

Optical proximity correction

10.1109/iwaps54037.2021.9671058

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Citations (1)

Impedance matching design of small normal mode helical antennas for RFID tags

International Symposium on Antennas and Propagation (2013)

Yi Liao Yuan Zhang Kun Cai Zichang Liang

The normal mode helical antenna (NMHA) is widely used on RFID applications because it fits well with the requirements of smaller physical size and high inductive impedance. In this paper, a power transmission coefficient method of mapping a modified impedance function onto the conventional Smith chart is applied to conjugate matching design between NMHA and chips. Moreover, the effect of various geometrical parameters of NMHA on resonant frequency and input impedance is investigated. Some significant characteristics of NMHA in the Smith chart are obtained by varying each parameter. It could provide an effective guidance to tune the antenna to desirable complex impedance in the Smith chart. Finally, impedance matching design of a specific NMHA is conducted according to the previously mentioned method.

Smith chart

Image impedance

Mode (computer interface)

Characteristic impedance

Antenna tuner

Source

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Citations (4)