Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996875
R. H. Bhuiyan, Mohammod Ali
A novel double meander PIFA with a parasitic metal box is proposed which can operate from 698 MHz to 960 MHz and is suitable for multimedia and voice communication in 4G mobile phones. A metal box in the vicinity of the PIFA is placed to improve the bandwidth and shift the operating frequency band lower. The antenna has good radiation pattern coverage over the whole frequency band and the cross polarization level is below −15 dB.
{"title":"A double meander PIFA with a parasitic metal box for wideband 4G mobile phones","authors":"R. H. Bhuiyan, Mohammod Ali","doi":"10.1109/APS.2011.5996875","DOIUrl":"https://doi.org/10.1109/APS.2011.5996875","url":null,"abstract":"A novel double meander PIFA with a parasitic metal box is proposed which can operate from 698 MHz to 960 MHz and is suitable for multimedia and voice communication in 4G mobile phones. A metal box in the vicinity of the PIFA is placed to improve the bandwidth and shift the operating frequency band lower. The antenna has good radiation pattern coverage over the whole frequency band and the cross polarization level is below −15 dB.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"31 1","pages":"1914-1917"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89054259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996472
J. Simon, A. Cheraly
This paper is based on research conducted by ONERA the French Aerospace Lab) for efficiently calculate the RCS of an air intake of an aircraft. The multidomain and multi-method (MD2M) coupling scheme, called FACTOPO [1], is based on generalized scattering matrix computation on three-dimensional subdomains. The global target is split in NV subdomains (Vi) separed by NI fictitious surfaces Γj (Figure 1. ). We use a modal representation of the tangent fields on the interfaces. In each domain, the generalized Scattering matrix Si is computed independently of the others using the most appropriate method (MLFMM, direct solver taking into account symmetries [2], asymptotic method …). This coupling scheme leads to an important reduction in computational resources. The advantages of this formulation for parametric studies will be illustrated by the computing of the RCS of an air-intake with turning engine.
{"title":"PAME tools for RCS prediction and NCTI applications: Methodology and prediction for the French channel model","authors":"J. Simon, A. Cheraly","doi":"10.1109/APS.2011.5996472","DOIUrl":"https://doi.org/10.1109/APS.2011.5996472","url":null,"abstract":"This paper is based on research conducted by ONERA the French Aerospace Lab) for efficiently calculate the RCS of an air intake of an aircraft. The multidomain and multi-method (MD2M) coupling scheme, called FACTOPO [1], is based on generalized scattering matrix computation on three-dimensional subdomains. The global target is split in NV subdomains (Vi) separed by NI fictitious surfaces Γj (Figure 1. ). We use a modal representation of the tangent fields on the interfaces. In each domain, the generalized Scattering matrix Si is computed independently of the others using the most appropriate method (MLFMM, direct solver taking into account symmetries [2], asymptotic method …). This coupling scheme leads to an important reduction in computational resources. The advantages of this formulation for parametric studies will be illustrated by the computing of the RCS of an air-intake with turning engine.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"15 1","pages":"1096-1099"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89202654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996545
R. Sharma, J. Wallace
Two methods are developed that can be applied to generate secret keys automatically from fading propagation channels that are reciprocal but have arbitrary (i.e. non Gaussian) statistics. Such methods may be necessary for physical-layer key generation in cases where the line-of-sight (LOS) component produces Rician channel statistics, not only because channel quantization based on Gaussian statistics will not provide equally probable symbols, but also because the symbol error rate (SER) and efficiency analysis based on Gaussian channels does not reflect true performance. An improved channel quantization method compared to [1], [2] is developed, where the empirical cumulative distribution function (cdf) of the channel is used directly to ensure equal probability of the key symbols. The results show that LOS channels can have slightly better SER performance than strictly Gaussian channels, especially at low SNR. Second, the idea of positional coding is developed, where a secret key can be transmitted by dividing empirical channel observations into multiple codewords and conveying a secret message from Alice to Bob in the sequence of channels fed forward from Alice to Bob. Analysis of the method illustrates that key mismatch rate can be made arbitrarily low by properly selecting the codeword length.
{"title":"Physical layer key generation methods for arbitrary fading channels","authors":"R. Sharma, J. Wallace","doi":"10.1109/APS.2011.5996545","DOIUrl":"https://doi.org/10.1109/APS.2011.5996545","url":null,"abstract":"Two methods are developed that can be applied to generate secret keys automatically from fading propagation channels that are reciprocal but have arbitrary (i.e. non Gaussian) statistics. Such methods may be necessary for physical-layer key generation in cases where the line-of-sight (LOS) component produces Rician channel statistics, not only because channel quantization based on Gaussian statistics will not provide equally probable symbols, but also because the symbol error rate (SER) and efficiency analysis based on Gaussian channels does not reflect true performance. An improved channel quantization method compared to [1], [2] is developed, where the empirical cumulative distribution function (cdf) of the channel is used directly to ensure equal probability of the key symbols. The results show that LOS channels can have slightly better SER performance than strictly Gaussian channels, especially at low SNR. Second, the idea of positional coding is developed, where a secret key can be transmitted by dividing empirical channel observations into multiple codewords and conveying a secret message from Alice to Bob in the sequence of channels fed forward from Alice to Bob. Analysis of the method illustrates that key mismatch rate can be made arbitrarily low by properly selecting the codeword length.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"242 1","pages":"1368-1371"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91460596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996956
H. Khaleel, H. Al‐Rizzo, D. Rucker, Yasir Rahmatallah, S. Mohan
In this paper, a μ-Negative metamaterial (MNG) is utilized for mutual coupling reduction between dual-band printed monopole antennas used in Multiple Input Multiple Output (MIMO). A dual-band MNG metamaterial is designed to specifically possess negative effective permeability at the two resonant frequencies where the antennas are operating. MNG is inserted between the two printed monopoles (back to back) to decrease the correlation between them. The printed monopole antennas were designed to operate in the Wireless Local Area Network (WLAN) bands 2.45 GHz and 5.2 GHz. Antenna characteristics such as, scattering parameters far-field radiation patterns with and without the presence of MNG are provided. The design of the MNG unit cell and its effective constitutive parameters are also provided. Design and simulations are conducted using Ansoft's HFSS software which is based on the Finite Element Method (FEM). The proposed technique achieved a 14 dB reduction in mutual coupling at 2.45 GHz and 13 dB at 5.2 GHz. A gain of 2 dB higher than the normal case at the second band is observed while it is maintained the same on the first band. Furthermore, the MNG based antenna system maintains a relatively low profile (16 mm) which is convenient for compact systems and hand-held devices.
{"title":"Mutual coupling reduction of dual-band printed monopoles using MNG metamaterial","authors":"H. Khaleel, H. Al‐Rizzo, D. Rucker, Yasir Rahmatallah, S. Mohan","doi":"10.1109/APS.2011.5996956","DOIUrl":"https://doi.org/10.1109/APS.2011.5996956","url":null,"abstract":"In this paper, a μ-Negative metamaterial (MNG) is utilized for mutual coupling reduction between dual-band printed monopole antennas used in Multiple Input Multiple Output (MIMO). A dual-band MNG metamaterial is designed to specifically possess negative effective permeability at the two resonant frequencies where the antennas are operating. MNG is inserted between the two printed monopoles (back to back) to decrease the correlation between them. The printed monopole antennas were designed to operate in the Wireless Local Area Network (WLAN) bands 2.45 GHz and 5.2 GHz. Antenna characteristics such as, scattering parameters far-field radiation patterns with and without the presence of MNG are provided. The design of the MNG unit cell and its effective constitutive parameters are also provided. Design and simulations are conducted using Ansoft's HFSS software which is based on the Finite Element Method (FEM). The proposed technique achieved a 14 dB reduction in mutual coupling at 2.45 GHz and 13 dB at 5.2 GHz. A gain of 2 dB higher than the normal case at the second band is observed while it is maintained the same on the first band. Furthermore, the MNG based antenna system maintains a relatively low profile (16 mm) which is convenient for compact systems and hand-held devices.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"119 4","pages":"2219-2222"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91491531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5997091
E. Lier, R. K. Shaw, M. Cuchanski, Shirley Yang
Two improvements to the previous work in meta-horn MBAs were presented. First, it was shown that meta-horn's improved directivity over conventional horns can be used to increase MBA beam resolution by using smaller horns. Second, it was shown that secondary pattern beam congruency can be achieved by specifically designing the meta-horn to follow a decreasing aperture efficiency versus frequency curve.
{"title":"Meta-horns improve the performance of multi-beam reflector antennas","authors":"E. Lier, R. K. Shaw, M. Cuchanski, Shirley Yang","doi":"10.1109/APS.2011.5997091","DOIUrl":"https://doi.org/10.1109/APS.2011.5997091","url":null,"abstract":"Two improvements to the previous work in meta-horn MBAs were presented. First, it was shown that meta-horn's improved directivity over conventional horns can be used to increase MBA beam resolution by using smaller horns. Second, it was shown that secondary pattern beam congruency can be achieved by specifically designing the meta-horn to follow a decreasing aperture efficiency versus frequency curve.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"6 1","pages":"2736-2737"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88913264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996955
A. Kulkarni, S. Sharma
A compact low cost multiband antenna design is proposed for future 4G Long term evolution (LTE) wireless devices of USB size and Bluetooth headsets. The printed inverted F- antenna (PIFA) type antenna structure is on a 1.6mm thick FR4 substrate. The Antenna covers LTE band-3 (1710–1880MHz)/ DCS 1800 and LTE band-7 (2500–2690MHZ) based on S11 = −6dB matching criterion. Radiation efficiency above 65% in the lower band and 80% in the upper band is achieved. Next the Multiple-Input-Multiple-Output (MIMO) configuration of this antenna is investigated. The MIMO configuration shows an envelope correlation (ρ) value of 0.5 which meets the required industry standards. Radiation efficiency is always above 60% for the MIMO configuration. Measured and simulated data are presented in this paper.
{"title":"A compact multiband antenna with MIMO implementation for USB size 4G LTE wireless devices","authors":"A. Kulkarni, S. Sharma","doi":"10.1109/APS.2011.5996955","DOIUrl":"https://doi.org/10.1109/APS.2011.5996955","url":null,"abstract":"A compact low cost multiband antenna design is proposed for future 4G Long term evolution (LTE) wireless devices of USB size and Bluetooth headsets. The printed inverted F- antenna (PIFA) type antenna structure is on a 1.6mm thick FR4 substrate. The Antenna covers LTE band-3 (1710–1880MHz)/ DCS 1800 and LTE band-7 (2500–2690MHZ) based on S11 = −6dB matching criterion. Radiation efficiency above 65% in the lower band and 80% in the upper band is achieved. Next the Multiple-Input-Multiple-Output (MIMO) configuration of this antenna is investigated. The MIMO configuration shows an envelope correlation (ρ) value of 0.5 which meets the required industry standards. Radiation efficiency is always above 60% for the MIMO configuration. Measured and simulated data are presented in this paper.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"28 1","pages":"2215-2218"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80697710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5997000
N. Sood, Liang Liang, S. Hum, C. Sarris
Ray tracing based on geometric optics can be utilized for generating propagation models for arbitrary and complex environments. These methods can be employed to determine important wireless channel characteristics such as coherence and delay spread. In this paper, an image theory based ray tracing method is used to study ultra-wideband propagation in complex tunnel environments such as curved tunnels and bifurcations. To validate the model, simulation results were compared to the experimental measurements performed in a hallway of an office building.
{"title":"Ray-tracing based modeling of ultra-wideband pulse propagation in railway tunnels","authors":"N. Sood, Liang Liang, S. Hum, C. Sarris","doi":"10.1109/APS.2011.5997000","DOIUrl":"https://doi.org/10.1109/APS.2011.5997000","url":null,"abstract":"Ray tracing based on geometric optics can be utilized for generating propagation models for arbitrary and complex environments. These methods can be employed to determine important wireless channel characteristics such as coherence and delay spread. In this paper, an image theory based ray tracing method is used to study ultra-wideband propagation in complex tunnel environments such as curved tunnels and bifurcations. To validate the model, simulation results were compared to the experimental measurements performed in a hallway of an office building.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"338 1","pages":"2383-2386"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80714022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996853
S. Raza, M. Antoniades, G. Eleftheriades
A compact and low-profile high-impedance surface is proposed which offers a significantly smaller footprint without affecting the usable reflection phase bandwidth of the structure. The unit cell of the proposed surface is similar to the traditional ‘mushroom’ structure, but utilizes inter-digitated-capacitor and spiral-inductor lumped elements to reduce its size without sacrificing the in-phase reflection bandwidth. It is determined that the reflection-phase resonance and bandwidth is largely independent of the shunt inductive loading and depends primarily on the value of the series capacitive loading. Finally, an application of the structure as a high-impedance ground plane for a printed loop antenna is proposed.
{"title":"A compact low-profile high-impedance surface for use as an antenna ground plane","authors":"S. Raza, M. Antoniades, G. Eleftheriades","doi":"10.1109/APS.2011.5996853","DOIUrl":"https://doi.org/10.1109/APS.2011.5996853","url":null,"abstract":"A compact and low-profile high-impedance surface is proposed which offers a significantly smaller footprint without affecting the usable reflection phase bandwidth of the structure. The unit cell of the proposed surface is similar to the traditional ‘mushroom’ structure, but utilizes inter-digitated-capacitor and spiral-inductor lumped elements to reduce its size without sacrificing the in-phase reflection bandwidth. It is determined that the reflection-phase resonance and bandwidth is largely independent of the shunt inductive loading and depends primarily on the value of the series capacitive loading. Finally, an application of the structure as a high-impedance ground plane for a printed loop antenna is proposed.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"92 1","pages":"1832-1835"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83762029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996710
Feng Wang, R. Lee
In this paper, we present an efficient hybrid method based on finite element (FE) and rigorous coupled wave analysis (RCWA) to model scattering from 3-D doubly periodic dielectric structures. The mode expansion technique is used as boundary truncation scheme. This scheme allows truncation boundaries to be placed close to dielectric grating, thus significantly reduces the size of the problem. Comparisons with finite element/boundary integral method, as well as, FE/RCWA with perfectly matched layer (PML), will be given for accuracy validation.
{"title":"Fast hybrid method for modeling scattering from doubly periodic dielectric structure in 3-D","authors":"Feng Wang, R. Lee","doi":"10.1109/APS.2011.5996710","DOIUrl":"https://doi.org/10.1109/APS.2011.5996710","url":null,"abstract":"In this paper, we present an efficient hybrid method based on finite element (FE) and rigorous coupled wave analysis (RCWA) to model scattering from 3-D doubly periodic dielectric structures. The mode expansion technique is used as boundary truncation scheme. This scheme allows truncation boundaries to be placed close to dielectric grating, thus significantly reduces the size of the problem. Comparisons with finite element/boundary integral method, as well as, FE/RCWA with perfectly matched layer (PML), will be given for accuracy validation.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"16 1","pages":"331-334"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79599684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5997104
F. Heereman, W. Joseph, E. Tanghe, D. Plets, L. Martens
In this paper, a path loss (PL) model for 802.11n in large conference rooms is determined, based on PL measurements. The PL can be described accurately by a one-slope model with one standard deviation. PL exponents varying from 1.2 to 1.7 are found. Based on this PL model, the effect of frequency (2.4 vs 5 GHz), configuration (SISO vs MIMO (spatial diversity)), bandwidth (20 vs 40 MHz) and transmit power on number of access points, total power consumption and possible (physical) throughputs is investigated. According to the determined PL model, a higher range (by tuning the transmit power) requires less access points, as well as a lower total power consumption, due to a PL exponent lower than 2.
在本文中，基于路径损耗(PL)测量确定了大型会议室中802.11n的路径损耗(PL)模型。PL可以用一个标准差的单斜率模型准确地描述。发现PL指数在1.2到1.7之间变化。基于该PL模型，研究了频率(2.4 vs 5 GHz)、配置(SISO vs MIMO(空间分集))、带宽(20 vs 40 MHz)和发射功率对接入点数量、总功耗和可能的(物理)吞吐量的影响。根据确定的PL模型，更高的范围(通过调整发射功率)需要更少的接入点，以及更低的总功耗，因为PL指数低于2。
{"title":"Development of path loss model for 802.11n in large conference rooms","authors":"F. Heereman, W. Joseph, E. Tanghe, D. Plets, L. Martens","doi":"10.1109/APS.2011.5997104","DOIUrl":"https://doi.org/10.1109/APS.2011.5997104","url":null,"abstract":"In this paper, a path loss (PL) model for 802.11n in large conference rooms is determined, based on PL measurements. The PL can be described accurately by a one-slope model with one standard deviation. PL exponents varying from 1.2 to 1.7 are found. Based on this PL model, the effect of frequency (2.4 vs 5 GHz), configuration (SISO vs MIMO (spatial diversity)), bandwidth (20 vs 40 MHz) and transmit power on number of access points, total power consumption and possible (physical) throughputs is investigated. According to the determined PL model, a higher range (by tuning the transmit power) requires less access points, as well as a lower total power consumption, due to a PL exponent lower than 2.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"19 1","pages":"2785-2788"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79700656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：