In this paper, an ultra-compact single negative（SNG） electric waveguided metamaterial（WG-MTM） is first investigated and used to reduce the mutual coupling in E ＆ H planes of a dual-band microstrip antenna array. ...In this paper, an ultra-compact single negative（SNG） electric waveguided metamaterial（WG-MTM） is first investigated and used to reduce the mutual coupling in E ＆ H planes of a dual-band microstrip antenna array. The proposed SNG electric WG-MTM unit cell is designed by etching two different symmetrical spiral lines on the ground, and has two stopbands operating at 1.86 GHz and 2.40 GHz. The circuit size is very compact, which is only λ_0/33.6 ×λ_0/15.1（where λ_0 is the wavelength at 1.86 GHz in free space）. Taking advantage of the dual-stopband property of the proposed SNG electric WG-MTM, a dual-band microstrip antenna array operating at 1.86 GHz and 2.40 GHz with very low mutual coupling is designed by embedding a cross shaped array of the proposed SNG electric WG-MTM. The measured and simulated results of the designed dual-band antenna array are in good agreement with each other, indicating that the mutual coupling of the fabricated dual-band antenna array realizes 9.8/11.1 d B reductions in the H plane, 8.5/7.9 d B reductions in the E plane at1.86 GHz and 2.40 GHz, respectively. Besides, the distance of the antenna elements in the array is only 0.35 λ_0（where λ_0 is the wavelength at 1.86 GHz in free space）. The proposed strategy is used for the first time to reduce the mutual coupling in E ＆ H planes of the dual-band microstrip antenna array by using ultra-compact SNG electric WG-MTM.展开更多
An ultra-compact hybrid-integration receiver optical subassembly(ROSA) with four channels is demonstrated in our laboratory with the size of 23.3 mm × 6.0 mm × 6.5 mm. The ROSA is comprised of a planar light...An ultra-compact hybrid-integration receiver optical subassembly(ROSA) with four channels is demonstrated in our laboratory with the size of 23.3 mm × 6.0 mm × 6.5 mm. The ROSA is comprised of a planar lightwave circuit(PLC) arrayed waveguide grating(AWG) chip, a top-illuminated positive-intrinsic-negative photodetector array chip, and a three-dimensional microwave circuit that is specially designed for compact packaging. For each transmission lane, the -3 dB bandwidth of the ROSA is up to 20 GHz, and the maximum responsivity is up to 0.53 A/W. The proposed package structure can be used for smaller package sizes and would be an easy assembling solution for 100 GbE optical communication devices.展开更多
The flame stability limit and propagation characteristics of a reverse-flow combustor without any flame-stabilized device were experimentally investigated under room temperature and pressure.The results indicate that ...The flame stability limit and propagation characteristics of a reverse-flow combustor without any flame-stabilized device were experimentally investigated under room temperature and pressure.The results indicate that it is feasible to stabilize the flame in the recirculation zones constructed by the impact jet flow from the primary holes and dilution holes.The flame projected area is mainly distributed in the recirculation zone upstream of the primary holes,whose presence and absence mark the ignition and extinction.During the ignition process,the growth rate and value of the flame projected area first increase and then decrease with the inlet velocity increasing from 9.4 m/s to 42.1 m/s.A rapid reduction followed by a slow reduction of ignition and lean blowout equivalence ratios is achieved by the increased inlet velocity.Then the non-reacting fluid structure in three sections was measured,and detailed velocity profiles were analyzed to improve the understanding of the flame stabilization mechanism.The results are conducive to the design of an ultra-compact combustor.展开更多
Based on the traditional directional coupler, we proposed a scheme to design on-chip polarization beam splitters using an inverse design method. In our scheme, the coupling area of the designed devices are only 0.48 ...Based on the traditional directional coupler, we proposed a scheme to design on-chip polarization beam splitters using an inverse design method. In our scheme, the coupling area of the designed devices are only 0.48 μm× 6.4 μm. By manipulating the refractive index of the coupling region, the devices can work in C-band,L-band, O-band, or any other communication band. Different from conventional design methods, which need to adjust the design parameters artificially, if the initial conditions are determined, the proposed scheme can automatically adjust the design parameters of devices according to specific requirements. The simulation results show that the insertion losses of the designed polarization beam splitters can be less than 0.4 dB(0.35 dB) for TE(TM)mode at the wavelengths of 1310, 1550, and 1600 nm, and the extinction ratios are larger than 19.9 dB for the TE and TM modes at all three wavelengths. Besides, the extinction ratios of both polarization states are more than 14.5 dB within the wavelength range of 1286–1364 nm, 1497–1568 nm, and 1553–1634 nm. At the same time,the insertion losses are smaller than 0.46 dB.展开更多
针对深厚杂填土地基的一次性处理要求土体密实度与均匀度的需求,以山西阳泉某独立储能电站工程为背景,开展20 000 k N·m与25 000 k N·m超高能级强夯技术的对比试验与效果评价。通过夯沉量动态监测、重型动力触探试验(DPT)、...针对深厚杂填土地基的一次性处理要求土体密实度与均匀度的需求,以山西阳泉某独立储能电站工程为背景,开展20 000 k N·m与25 000 k N·m超高能级强夯技术的对比试验与效果评价。通过夯沉量动态监测、重型动力触探试验(DPT)、平板载荷试验(PLT)、压缩模量试验及瑞利波测试,并分析强夯加固效果。结果表明:综合重型动力触探试验(DPT)与平板载荷试验(PLT)结果,25 000 k N·m和20 000 k N·m能级强夯的有效加固深度分别达到18.0 m和16.0 m,经两种能级处理后的杂填土地基承载力特征值均不低于200 k Pa,有效加固范围内土体压缩模量达到15 MPa;根据地面下16 m深度范围内瑞利面波测试数据,25 000 k N·m和20 000 k N·m能级强夯后的波速分别提高了34.4%和60.9%,证实了杂填土地基密实度的显著提升。随着夯击遍数增加,两种能级强夯的累计夯沉量均呈现逐遍递减趋势,表明地基土体密实度与均匀性得到显著改善。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61372034)
文摘In this paper, an ultra-compact single negative（SNG） electric waveguided metamaterial（WG-MTM） is first investigated and used to reduce the mutual coupling in E ＆ H planes of a dual-band microstrip antenna array. The proposed SNG electric WG-MTM unit cell is designed by etching two different symmetrical spiral lines on the ground, and has two stopbands operating at 1.86 GHz and 2.40 GHz. The circuit size is very compact, which is only λ_0/33.6 ×λ_0/15.1（where λ_0 is the wavelength at 1.86 GHz in free space）. Taking advantage of the dual-stopband property of the proposed SNG electric WG-MTM, a dual-band microstrip antenna array operating at 1.86 GHz and 2.40 GHz with very low mutual coupling is designed by embedding a cross shaped array of the proposed SNG electric WG-MTM. The measured and simulated results of the designed dual-band antenna array are in good agreement with each other, indicating that the mutual coupling of the fabricated dual-band antenna array realizes 9.8/11.1 d B reductions in the H plane, 8.5/7.9 d B reductions in the E plane at1.86 GHz and 2.40 GHz, respectively. Besides, the distance of the antenna elements in the array is only 0.35 λ_0（where λ_0 is the wavelength at 1.86 GHz in free space）. The proposed strategy is used for the first time to reduce the mutual coupling in E ＆ H planes of the dual-band microstrip antenna array by using ultra-compact SNG electric WG-MTM.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61625504,61727815,61535014,61527820,and 11674313)
文摘An ultra-compact hybrid-integration receiver optical subassembly(ROSA) with four channels is demonstrated in our laboratory with the size of 23.3 mm × 6.0 mm × 6.5 mm. The ROSA is comprised of a planar lightwave circuit(PLC) arrayed waveguide grating(AWG) chip, a top-illuminated positive-intrinsic-negative photodetector array chip, and a three-dimensional microwave circuit that is specially designed for compact packaging. For each transmission lane, the -3 dB bandwidth of the ROSA is up to 20 GHz, and the maximum responsivity is up to 0.53 A/W. The proposed package structure can be used for smaller package sizes and would be an easy assembling solution for 100 GbE optical communication devices.
基金supported by the National Nature Science Foundation of China through Grant No.51506086the Jiangsu Funding Program for Excellent Postdoctoral Talent(No.316958)+3 种基金the Natural Science Foundation of Jiangsu Province,China(BK20230932)the China Postdoctoral Science Foundation(No.2023M741697)the Fundamental Research Funds for the Central Universities(No.30923010306)the financial support from Low-carbon Aerospace Power Engineering Research Center of Ministry of Education(CEPE2020018)。
文摘The flame stability limit and propagation characteristics of a reverse-flow combustor without any flame-stabilized device were experimentally investigated under room temperature and pressure.The results indicate that it is feasible to stabilize the flame in the recirculation zones constructed by the impact jet flow from the primary holes and dilution holes.The flame projected area is mainly distributed in the recirculation zone upstream of the primary holes,whose presence and absence mark the ignition and extinction.During the ignition process,the growth rate and value of the flame projected area first increase and then decrease with the inlet velocity increasing from 9.4 m/s to 42.1 m/s.A rapid reduction followed by a slow reduction of ignition and lean blowout equivalence ratios is achieved by the increased inlet velocity.Then the non-reacting fluid structure in three sections was measured,and detailed velocity profiles were analyzed to improve the understanding of the flame stabilization mechanism.The results are conducive to the design of an ultra-compact combustor.
基金National Natural Science Foundation of China(NSFC)(60907003)Natural Science Foundation of Hunan Province(13JJ3001)+1 种基金Program for New Century Excellent Talents in University(NCET)(NCET-12-0142)Foundation of NUDT(JC13-02-13)
文摘Based on the traditional directional coupler, we proposed a scheme to design on-chip polarization beam splitters using an inverse design method. In our scheme, the coupling area of the designed devices are only 0.48 μm× 6.4 μm. By manipulating the refractive index of the coupling region, the devices can work in C-band,L-band, O-band, or any other communication band. Different from conventional design methods, which need to adjust the design parameters artificially, if the initial conditions are determined, the proposed scheme can automatically adjust the design parameters of devices according to specific requirements. The simulation results show that the insertion losses of the designed polarization beam splitters can be less than 0.4 dB(0.35 dB) for TE(TM)mode at the wavelengths of 1310, 1550, and 1600 nm, and the extinction ratios are larger than 19.9 dB for the TE and TM modes at all three wavelengths. Besides, the extinction ratios of both polarization states are more than 14.5 dB within the wavelength range of 1286–1364 nm, 1497–1568 nm, and 1553–1634 nm. At the same time,the insertion losses are smaller than 0.46 dB.
文摘针对深厚杂填土地基的一次性处理要求土体密实度与均匀度的需求,以山西阳泉某独立储能电站工程为背景,开展20 000 k N·m与25 000 k N·m超高能级强夯技术的对比试验与效果评价。通过夯沉量动态监测、重型动力触探试验(DPT)、平板载荷试验(PLT)、压缩模量试验及瑞利波测试,并分析强夯加固效果。结果表明:综合重型动力触探试验(DPT)与平板载荷试验(PLT)结果,25 000 k N·m和20 000 k N·m能级强夯的有效加固深度分别达到18.0 m和16.0 m,经两种能级处理后的杂填土地基承载力特征值均不低于200 k Pa,有效加固范围内土体压缩模量达到15 MPa;根据地面下16 m深度范围内瑞利面波测试数据,25 000 k N·m和20 000 k N·m能级强夯后的波速分别提高了34.4%和60.9%,证实了杂填土地基密实度的显著提升。随着夯击遍数增加,两种能级强夯的累计夯沉量均呈现逐遍递减趋势,表明地基土体密实度与均匀性得到显著改善。
