Heavy metals,notably Pb2+and Cu^(2+),are some of the most persistent contaminants found in groundwater.Frequent monitoring of these metals,which relies on efficient,sensitive,cost-effective,and reliable methods,is a n...Heavy metals,notably Pb2+and Cu^(2+),are some of the most persistent contaminants found in groundwater.Frequent monitoring of these metals,which relies on efficient,sensitive,cost-effective,and reliable methods,is a necessity.We present a nanocomposite-based miniaturized electrode for the concurrent measurement of Pb2+and Cu^(2+)by exploiting the electroanalytical technique of square wave voltammetry.We also propose a facile in situ hydrothermal calcination method to directly grow binder-free mesoporous Ni O on a three-dimensional nickel foam,which is then electrochemically seeded with gold nanoparticles(Au NPs).The meticulous design of a low-barrier Ohmic contact between mesoporous Ni O and Au NPs facilitates target-mediated nanochannel-confined electron transfer within mesoporous Ni O.As a result,the heavy metals Pb2+(0.020 mg.L^(-1)detection limit;2.0–16.0 mg.L^(-1)detection range)and Cu^(2+)(0.013 mg.L^(-1)detection limit;0.4–12.8 mg.L^(-1)detection range)can be detected simultaneously with high precision.Furthermore,other heavy metal ions and common interfering ions found in groundwater showed negligible impacts on the electrode’s performance,and the recovery rate of groundwater samples varied between 96.3%±2.1%and 109.4%±0.6%.The compactness,flexible shape,low power consumption,and ability to remotely operate our electrode pave the way for onsite detection of heavy metals in groundwater,thereby demonstrating the potential to revolutionize the field of environmental monitoring.展开更多
AIM To compare the outcomes of retrograde intrarenal surgery(RIRS) and miniaturized percutaneous nephrolithotomy(mini-PCNL) in treating lower pole(LP) renal stones with a diameter of 1.5-2.5 cm.METHODS A total of 216 ...AIM To compare the outcomes of retrograde intrarenal surgery(RIRS) and miniaturized percutaneous nephrolithotomy(mini-PCNL) in treating lower pole(LP) renal stones with a diameter of 1.5-2.5 cm.METHODS A total of 216 patients who underwent mini-PCNL(n = 103) or RIRS n = 113) for LP stones with a diameter of 1.5-2.5 cm were enrolled between December 2015 and April 2017 at the Urology Department of Ningbo Urology and Nephrology Hospital.RESULTS Significant differences were found in the hospital stay(9.39 ± 4.01 vs 14.08 ± 5.26, P < 0.0001) and hospitalization costs(2624.5 ± 513.36 vs 3255.2 ± 976.5, P < 0.0001) between the RIRS and mini-PCNL groups. The mean operation time was not significantly different between the RIRS group(56.48 ± 24.77) and the mini-PCNL group(60.04 ± 30.38, P = 0.345). The stone-free rates at the first postoperative day(RIRS vs mini-PCNL: 90.2% vs 93.2%, P = 0.822) and the second month postoperatively(RIRS vs mini-PCNL: 93.8% vs 95.1%, P = 0.986) were not significantly different.CONCLUSION RIRS and mini-PCNL are both safe and effective methods for treating LP stones with a diameter of 1.5-2.5 cm. RIRS can be considered as an alternative to PCNL for the treatment for LP stones of 1.5-2.5 cm.展开更多
The rapid progress of micro/nanoelectronic systems and miniaturized portable devices has tremendously increased the urgent demands for miniaturized and integrated power supplies.Miniaturized energy storage devices(MES...The rapid progress of micro/nanoelectronic systems and miniaturized portable devices has tremendously increased the urgent demands for miniaturized and integrated power supplies.Miniaturized energy storage devices(MESDs),with their excellent properties and additional intelligent functions,are considered to be the preferable energy supplies for uninterrupted powering of microsystems.In this review,we aim to provide a comprehensive overview of the background,fundamentals,device configurations,manufacturing processes,and typical applications of MESDs,including their recent advances.Particular attention is paid to advanced device configurations,such as two-dimensional(2D)stacked,2D planar interdigital,2D arbitrary-shaped,three-dimensional planar,and wire-shaped structures,and their corresponding manufacturing strategies,such as printing,scribing,and masking techniques.Additionally,recent developments in MESDs,including microbatteries and microsupercapacitors,as well as microhybrid metal ion capacitors,are systematically summarized.A series of on-chip microsystems,created by integrating functional MESDs,are also highlighted.Finally,the remaining challenges and future research scope on MESDs are discussed.展开更多
The polypyrrole is the high conductive polymer which was coated onto indium tin oxide (ITO) glass substrate by electroplated technique to fabricate a miniaturized reference electrode.Besides,the morphology of the ITO...The polypyrrole is the high conductive polymer which was coated onto indium tin oxide (ITO) glass substrate by electroplated technique to fabricate a miniaturized reference electrode.Besides,the morphology of the ITO glass reference electrode electroplated with pyrrole has been studied through the instrumental analysis utilizing cyclic voltammetry (CV). Furthermore,the sensing characteristics of the reference electrode have been measured by using commercial instrumental amplifier as the readout circuit.Using the high conductive polymer as miniaturized reference electrode has many advantages such as easy fabrication of coating polymer,without any expensive fabricating equipment,easy carry by the miniaturized technique.Hence,it is suitable for the reference electrode production.展开更多
A miniaturized square resonator bandpass filter with circular stubs is designed, fabricated, and characterized. Analytical calculations were carried out to determine the critical filter parameters and the design was o...A miniaturized square resonator bandpass filter with circular stubs is designed, fabricated, and characterized. Analytical calculations were carried out to determine the critical filter parameters and the design was optimized using a 3D electromagnetic finite-element solver. The measured results were in good agreement with the designed results. The proposed filter exhibits significant improvement in bandwidth compared to the conventional square resonator bandpass filters.展开更多
The major source of morbidity following cardiopulmonary bypass (CPB) is the systemic inflammatory response (SIRS response) which leads to multiple derangements in different organ systems. To combat this, miniaturized ...The major source of morbidity following cardiopulmonary bypass (CPB) is the systemic inflammatory response (SIRS response) which leads to multiple derangements in different organ systems. To combat this, miniaturized cardiopulmonary bypass circuits (MCPBC) have been created to lessen the inflammatory response to CPB. Here we examine early outcomes following coronary artery bypass grafting (CABG) using a MCPBC system compared to conventional bypass techniques at a single institution. Methods: 60 consecutive patients undergoing elective CABG were prospectively enrolled. Nine patients underwent coronary artery bypass grafting (CABG) with conventional CPB (cCABG), 33 underwent off-pump CABG (OPCAB), and the remaining 18 patients underwent CABG with a MCPBC system. Demographics and outcomes were compared between groups and statistical analyses applied. Results: No significant difference was observed in mortality between groups, with only one death reported in total. Morbidity was also low, totaling only 6.7%, with none occurring in the MCPBC group. The MCPBC group required less PRBC and total blood product transfusion than the cCABG and OPCABG groups (p = 0.05), but changes in PLT and Hct over time were not different between groups. Conclusions: The MCPBC system was shown to be comparable to conventional bypass and OPCABG in terms of postoperative complications and mortality. Furthermore, the MCPBC system had the advantage of a decreased transfusion requirement. Based on our preliminary observations, this mini-cardiopulmonary bypass circuit provides a safe alternative to conventional bypass techniques.展开更多
In this paper, a new miniaturized wide-pass-band filter at U band based on composite right/left- handed transmission line (CRLH TL) is implemented. The CRLH TL contributed to a broadband filter is a balanced structure...In this paper, a new miniaturized wide-pass-band filter at U band based on composite right/left- handed transmission line (CRLH TL) is implemented. The CRLH TL contributed to a broadband filter is a balanced structure with a small size of only 1.428 mm*0.5530 mm. The frequency characteristics are simulated and the results show that the 3 dB band width of the proposed filter is about 13.5 GHz from 45.8 GHz to 59.3 GHz. The insertion loss is quite flat through the pass-band and the return loss is relatively low.展开更多
China Asia-Pacific Mobile Telecommunications Satellite Co., Ltd. (China APMT) has signed a QB50 Project Memorandum of Understanding with the Von Karman Institute for Fluid Dynamics (VKI). According to the agreement, C...China Asia-Pacific Mobile Telecommunications Satellite Co., Ltd. (China APMT) has signed a QB50 Project Memorandum of Understanding with the Von Karman Institute for Fluid Dynamics (VKI). According to the agreement, China APMT will launch 50 miniaturized satellites for VKI from 2014-15.展开更多
This paper presents a miniaturized microstrip branch-line coupler with good harmonic suppression performance. The proposed coupler consists of four branch-line sections, each of which is loaded by open-circuit stubs b...This paper presents a miniaturized microstrip branch-line coupler with good harmonic suppression performance. The proposed coupler consists of four branch-line sections, each of which is loaded by open-circuit stubs both at the center and the two ends. This type of loading can realize size reduction and harmonic suppression. As an example, a proposed branch-line coupler operating at 1.0 GHz is designed, fabricated and measured. The results show that the proposed branch-line coupler occupies 67% size of a conventional one and has better than 20 dB suppression from 1.9 to 5.8 GHz. Furthermore, the high slop of the transition band ensures good selectivity of the coupler.展开更多
An acoustically actuated piezoelectric antenna is proposed for low frequency(LF)band in this paper.The proposed antenna is theoretically calculated,numerically optimized by the finite element method(FEM),and experimen...An acoustically actuated piezoelectric antenna is proposed for low frequency(LF)band in this paper.The proposed antenna is theoretically calculated,numerically optimized by the finite element method(FEM),and experimentally analyzed.The measurement results show that the near-field radiation pattern of the piezoelectric antenna is similar to that of the electric dipole antenna.The radiation efficiency of the piezoelectric antenna is 3-4 orders of magnitude higher than that of electrically small antenna(ESA),with their sizes being the same size,and the maximum transmission distance obtained experimentally is 100 cm,which can be improved by increasing the input power.In addition,the gain,directivity,and quality factor of piezoelectric antenna are also analyzed.In this paper,traditional antenna parameters are creatively used to analyze the performance of piezoelectric antenna.The research conclusions can provide reliable theoretical basis for realizing LF antenna miniaturization.展开更多
Miniaturization of Frequency Selective Surface's ( FSS's) size is significant for its application in the limited space. In this paper, a novel methodology for designing low-profile FSS is discussed, and a corr...Miniaturization of Frequency Selective Surface's ( FSS's) size is significant for its application in the limited space. In this paper, a novel methodology for designing low-profile FSS is discussed, and a corresponding multi-layer structure with lumped elements for band-pass response is presented. Based on the equivalent circuit theory,the inductive designed center layer is firstly discussed. Then different numbers of additional capacitive designed layers are added and their performances are presented. Finally,the lumped elements are added both between adjacent layers and between adjacent cells of the additional layers so that the miniaturization performance can be further improved. The simulations for each structure in waves of different polarizations and incident angles are conducted,and the results are presented,which demonstrate the claimed characteristics of the proposed structure.展开更多
A miniaturized 2.45 GHz permanent magnet electron cyclotron resonance(PMECR) ion source, which has the ability of producing a tens-m A H+beam, has been built and tested at Peking University(PKU). Its plasma chamber di...A miniaturized 2.45 GHz permanent magnet electron cyclotron resonance(PMECR) ion source, which has the ability of producing a tens-m A H+beam, has been built and tested at Peking University(PKU). Its plasma chamber dimension is Φ30 mm×40 mm and the whole size of the ion source is Φ180 mm×130 mm. This source has a unique structure with the whole source body embedded into the extraction system. It can be operated in both continuous wave(CW) mode and pulse mode. In the CW mode, more than 20 m A hydrogen ion beam at 40 k V can be obtained with the microwave power of 180 W and about 1 m A hydrogen ion beam is produced with a microwave power of 10 W. In the pulse mode, more than50 m A hydrogen ion beam with a duty factor of 10% can be extracted when the peak microwave power is 1800 W.展开更多
Based on miniaturized components’ characteristics, the method of assembling miniaturized gear and shaft together with corresponding calculating model of the interference amount are proposed. On the basis of main effe...Based on miniaturized components’ characteristics, the method of assembling miniaturized gear and shaft together with corresponding calculating model of the interference amount are proposed. On the basis of main effecting factors analysis on the gear and shaft assembling interference amount, calculating formula including all factors effective on the interference amount necessary for reliable system running was built up. The methods of reverse calculating theoretical model was used to build up the equivalent simulation model of the theoretical one, together with simulation verification and case study for calculating formula. The results show that the cold assembling method is applicable for miniaturized gear and shaft, but in the assembling process, the interference amount compensating the shape error of contacting surfaces takes a large proportion, which is the main cause of stress variance on contacting surfaces.展开更多
This paper presents a novel miniaturized fiber-optic Fabry-Peort interferometer (FPI) for highly sensitive refractive index measurement. This device was tested for the refractive indices of various liquids including a...This paper presents a novel miniaturized fiber-optic Fabry-Peort interferometer (FPI) for highly sensitive refractive index measurement. This device was tested for the refractive indices of various liquids including acetone and ethanol at room temperature. The sensitivity for measurement of refractive index change of ethanol is 1138 nm/RIU at the wavelength of 1550 nm. In addition, the sensor fabrication is simple including only cleaving, splicing, and etching. The signal is stable with high visibility. Therefore, it provides a valuable tool in biological and chemical applications.展开更多
The generation of plasma in a microwave ion source involves confining electrons using a static magnetic field and energizing them with an electromagnetic field that transmitted into the plasma chamber.However,accordin...The generation of plasma in a microwave ion source involves confining electrons using a static magnetic field and energizing them with an electromagnetic field that transmitted into the plasma chamber.However,according to electromagnetics theory,there is always a cut-off size in circular wave guides for a given frequency.For a 2.45 GHz microwave,this dimension is 72 mm,which should theoretically prevent transmission of the microwave into the discharge chamber and no plasma can be generated.Since 2006 Peking University(PKU)has successfully developed a series of permanent magnet 2.45 GHz microwave ion sources(PKU PMECRs)with a discharge chamber less than 50 mm,capable of delivering tens of mA beams for accelerators.To explain this anomalous phenomenon,a hybrid discharge heating(HDH)mode that combines surface wave plasma and electron cyclotron heating has been proposed.This HDH mode not only successfully explains PKU PMECRs,but also predicts that the optimized inner diameter of the plasma chamber is 24 mm,which is confirmed by experiments involving different liners in the miniaturized microwave ion source.展开更多
Energetic Semiconductor bridge(ESCB)based on reactive multilayered films(RMFs)has a promising application in the miniature and intelligence of initiator and pyrotechnics device.Understanding the ignition enhancement m...Energetic Semiconductor bridge(ESCB)based on reactive multilayered films(RMFs)has a promising application in the miniature and intelligence of initiator and pyrotechnics device.Understanding the ignition enhancement mechanism of RMFs on semiconductor bridge(SCB)during the ignition process is crucial for the engineering and practical application of advanced initiator and pyrotechnics devices.In this study,a one-dimensional(1D)gas-solid two-phase flow ignition model was established to study the ignition process of ESCB to charge particles based on the reactivity of Al/MoO_(3) RMFs.In order to fully consider the coupled exothermic between the RMFs and the SCB plasma during the ignition process,the heat release of chemical reaction in RMFs was used as an internal heat source in this model.It is found that the exothermal reaction in RMFs improved the ignition performance of SCB.In the process of plasma rapid condensation with heat release,the product of RMFs enhanced the heat transfer process between the gas phase and the solid charge particle,which accelerated the expansion of hot plasma,and heated the solid charge particle as well as gas phase region with low temperature.In addition,it made up for pressure loss in the gas phase.During the plasma dissipation process,the exothermal chemical reaction in RMFs acted as the main heating source to heat the charge particle,making the surface temperature of the charge particle,gas pressure,and gas temperature rise continuously.This result may yield significant advantages in providing a universal ignition model for miniaturized ignition devices.展开更多
空射诱饵弹(miniature air launched decoy,MALD)可诱骗地面防空雷达开机,消耗防空弹药,降低地面防空装备作战效能,提升空中编队突防能力。在梳理空射诱饵弹发展概况基础上,分析空射诱饵弹目标特性,构建典型作战运用场景,开展MALD对制...空射诱饵弹(miniature air launched decoy,MALD)可诱骗地面防空雷达开机,消耗防空弹药,降低地面防空装备作战效能,提升空中编队突防能力。在梳理空射诱饵弹发展概况基础上,分析空射诱饵弹目标特性,构建典型作战运用场景,开展MALD对制导雷达探测跟踪性能和拦截效能影响分析,采用理论分析和动态仿真的方法研究了空射诱饵弹实施远距离欺骗、抵近干扰对制导雷达探测跟踪性能的影响,采用排队论方法分析MALD对空中编队突防效能的影响。研究结论可为空射诱饵弹战术运用提供参考。展开更多
基金supported by the National Key Research and Development Project of China(2019YFC1804802)。
文摘Heavy metals,notably Pb2+and Cu^(2+),are some of the most persistent contaminants found in groundwater.Frequent monitoring of these metals,which relies on efficient,sensitive,cost-effective,and reliable methods,is a necessity.We present a nanocomposite-based miniaturized electrode for the concurrent measurement of Pb2+and Cu^(2+)by exploiting the electroanalytical technique of square wave voltammetry.We also propose a facile in situ hydrothermal calcination method to directly grow binder-free mesoporous Ni O on a three-dimensional nickel foam,which is then electrochemically seeded with gold nanoparticles(Au NPs).The meticulous design of a low-barrier Ohmic contact between mesoporous Ni O and Au NPs facilitates target-mediated nanochannel-confined electron transfer within mesoporous Ni O.As a result,the heavy metals Pb2+(0.020 mg.L^(-1)detection limit;2.0–16.0 mg.L^(-1)detection range)and Cu^(2+)(0.013 mg.L^(-1)detection limit;0.4–12.8 mg.L^(-1)detection range)can be detected simultaneously with high precision.Furthermore,other heavy metal ions and common interfering ions found in groundwater showed negligible impacts on the electrode’s performance,and the recovery rate of groundwater samples varied between 96.3%±2.1%and 109.4%±0.6%.The compactness,flexible shape,low power consumption,and ability to remotely operate our electrode pave the way for onsite detection of heavy metals in groundwater,thereby demonstrating the potential to revolutionize the field of environmental monitoring.
基金Supported by the Ningbo Medical Science and Technology Project,No.2014A33
文摘AIM To compare the outcomes of retrograde intrarenal surgery(RIRS) and miniaturized percutaneous nephrolithotomy(mini-PCNL) in treating lower pole(LP) renal stones with a diameter of 1.5-2.5 cm.METHODS A total of 216 patients who underwent mini-PCNL(n = 103) or RIRS n = 113) for LP stones with a diameter of 1.5-2.5 cm were enrolled between December 2015 and April 2017 at the Urology Department of Ningbo Urology and Nephrology Hospital.RESULTS Significant differences were found in the hospital stay(9.39 ± 4.01 vs 14.08 ± 5.26, P < 0.0001) and hospitalization costs(2624.5 ± 513.36 vs 3255.2 ± 976.5, P < 0.0001) between the RIRS and mini-PCNL groups. The mean operation time was not significantly different between the RIRS group(56.48 ± 24.77) and the mini-PCNL group(60.04 ± 30.38, P = 0.345). The stone-free rates at the first postoperative day(RIRS vs mini-PCNL: 90.2% vs 93.2%, P = 0.822) and the second month postoperatively(RIRS vs mini-PCNL: 93.8% vs 95.1%, P = 0.986) were not significantly different.CONCLUSION RIRS and mini-PCNL are both safe and effective methods for treating LP stones with a diameter of 1.5-2.5 cm. RIRS can be considered as an alternative to PCNL for the treatment for LP stones of 1.5-2.5 cm.
基金the financial support from the National Natural Science Foundation of China(Grant Nos.51702095,51722503,51975204)Natural Science Foundation of Hunan Province,China(Grant No.2018JJ3041)+1 种基金the Fundamental Research Funds for the Central Universities(531118010016)Science and Technology Bureau Foundation of Changsha City(kh1904005)。
文摘The rapid progress of micro/nanoelectronic systems and miniaturized portable devices has tremendously increased the urgent demands for miniaturized and integrated power supplies.Miniaturized energy storage devices(MESDs),with their excellent properties and additional intelligent functions,are considered to be the preferable energy supplies for uninterrupted powering of microsystems.In this review,we aim to provide a comprehensive overview of the background,fundamentals,device configurations,manufacturing processes,and typical applications of MESDs,including their recent advances.Particular attention is paid to advanced device configurations,such as two-dimensional(2D)stacked,2D planar interdigital,2D arbitrary-shaped,three-dimensional planar,and wire-shaped structures,and their corresponding manufacturing strategies,such as printing,scribing,and masking techniques.Additionally,recent developments in MESDs,including microbatteries and microsupercapacitors,as well as microhybrid metal ion capacitors,are systematically summarized.A series of on-chip microsystems,created by integrating functional MESDs,are also highlighted.Finally,the remaining challenges and future research scope on MESDs are discussed.
文摘The polypyrrole is the high conductive polymer which was coated onto indium tin oxide (ITO) glass substrate by electroplated technique to fabricate a miniaturized reference electrode.Besides,the morphology of the ITO glass reference electrode electroplated with pyrrole has been studied through the instrumental analysis utilizing cyclic voltammetry (CV). Furthermore,the sensing characteristics of the reference electrode have been measured by using commercial instrumental amplifier as the readout circuit.Using the high conductive polymer as miniaturized reference electrode has many advantages such as easy fabrication of coating polymer,without any expensive fabricating equipment,easy carry by the miniaturized technique.Hence,it is suitable for the reference electrode production.
文摘A miniaturized square resonator bandpass filter with circular stubs is designed, fabricated, and characterized. Analytical calculations were carried out to determine the critical filter parameters and the design was optimized using a 3D electromagnetic finite-element solver. The measured results were in good agreement with the designed results. The proposed filter exhibits significant improvement in bandwidth compared to the conventional square resonator bandpass filters.
文摘The major source of morbidity following cardiopulmonary bypass (CPB) is the systemic inflammatory response (SIRS response) which leads to multiple derangements in different organ systems. To combat this, miniaturized cardiopulmonary bypass circuits (MCPBC) have been created to lessen the inflammatory response to CPB. Here we examine early outcomes following coronary artery bypass grafting (CABG) using a MCPBC system compared to conventional bypass techniques at a single institution. Methods: 60 consecutive patients undergoing elective CABG were prospectively enrolled. Nine patients underwent coronary artery bypass grafting (CABG) with conventional CPB (cCABG), 33 underwent off-pump CABG (OPCAB), and the remaining 18 patients underwent CABG with a MCPBC system. Demographics and outcomes were compared between groups and statistical analyses applied. Results: No significant difference was observed in mortality between groups, with only one death reported in total. Morbidity was also low, totaling only 6.7%, with none occurring in the MCPBC group. The MCPBC group required less PRBC and total blood product transfusion than the cCABG and OPCABG groups (p = 0.05), but changes in PLT and Hct over time were not different between groups. Conclusions: The MCPBC system was shown to be comparable to conventional bypass and OPCABG in terms of postoperative complications and mortality. Furthermore, the MCPBC system had the advantage of a decreased transfusion requirement. Based on our preliminary observations, this mini-cardiopulmonary bypass circuit provides a safe alternative to conventional bypass techniques.
文摘In this paper, a new miniaturized wide-pass-band filter at U band based on composite right/left- handed transmission line (CRLH TL) is implemented. The CRLH TL contributed to a broadband filter is a balanced structure with a small size of only 1.428 mm*0.5530 mm. The frequency characteristics are simulated and the results show that the 3 dB band width of the proposed filter is about 13.5 GHz from 45.8 GHz to 59.3 GHz. The insertion loss is quite flat through the pass-band and the return loss is relatively low.
文摘China Asia-Pacific Mobile Telecommunications Satellite Co., Ltd. (China APMT) has signed a QB50 Project Memorandum of Understanding with the Von Karman Institute for Fluid Dynamics (VKI). According to the agreement, China APMT will launch 50 miniaturized satellites for VKI from 2014-15.
基金Supported by the National Natural Science Foundation of China (No. 51007040)
文摘This paper presents a miniaturized microstrip branch-line coupler with good harmonic suppression performance. The proposed coupler consists of four branch-line sections, each of which is loaded by open-circuit stubs both at the center and the two ends. This type of loading can realize size reduction and harmonic suppression. As an example, a proposed branch-line coupler operating at 1.0 GHz is designed, fabricated and measured. The results show that the proposed branch-line coupler occupies 67% size of a conventional one and has better than 20 dB suppression from 1.9 to 5.8 GHz. Furthermore, the high slop of the transition band ensures good selectivity of the coupler.
文摘An acoustically actuated piezoelectric antenna is proposed for low frequency(LF)band in this paper.The proposed antenna is theoretically calculated,numerically optimized by the finite element method(FEM),and experimentally analyzed.The measurement results show that the near-field radiation pattern of the piezoelectric antenna is similar to that of the electric dipole antenna.The radiation efficiency of the piezoelectric antenna is 3-4 orders of magnitude higher than that of electrically small antenna(ESA),with their sizes being the same size,and the maximum transmission distance obtained experimentally is 100 cm,which can be improved by increasing the input power.In addition,the gain,directivity,and quality factor of piezoelectric antenna are also analyzed.In this paper,traditional antenna parameters are creatively used to analyze the performance of piezoelectric antenna.The research conclusions can provide reliable theoretical basis for realizing LF antenna miniaturization.
基金Sponsored by the National Natural Science Foundation of China(Grant No.60801015 and 61001036)the Special Funds Projects for Technological and Innovative Talent of Harbin City(Grant No.2010RFXXG010)+2 种基金the Fundamental Research Funds for the Central Universities(No.HIT.IBRSEM.2009 and HIT.NSRIF.201153)China Postdoctoral Science Foundation(Grant No.LBH-Z10126)Heilongjiang Province Postdoctoral Foundation(Grant No.20110491093)
文摘Miniaturization of Frequency Selective Surface's ( FSS's) size is significant for its application in the limited space. In this paper, a novel methodology for designing low-profile FSS is discussed, and a corresponding multi-layer structure with lumped elements for band-pass response is presented. Based on the equivalent circuit theory,the inductive designed center layer is firstly discussed. Then different numbers of additional capacitive designed layers are added and their performances are presented. Finally,the lumped elements are added both between adjacent layers and between adjacent cells of the additional layers so that the miniaturization performance can be further improved. The simulations for each structure in waves of different polarizations and incident angles are conducted,and the results are presented,which demonstrate the claimed characteristics of the proposed structure.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB845502)the National Natural Science Foundation of China(Grant No.11575013)
文摘A miniaturized 2.45 GHz permanent magnet electron cyclotron resonance(PMECR) ion source, which has the ability of producing a tens-m A H+beam, has been built and tested at Peking University(PKU). Its plasma chamber dimension is Φ30 mm×40 mm and the whole size of the ion source is Φ180 mm×130 mm. This source has a unique structure with the whole source body embedded into the extraction system. It can be operated in both continuous wave(CW) mode and pulse mode. In the CW mode, more than 20 m A hydrogen ion beam at 40 k V can be obtained with the microwave power of 180 W and about 1 m A hydrogen ion beam is produced with a microwave power of 10 W. In the pulse mode, more than50 m A hydrogen ion beam with a duty factor of 10% can be extracted when the peak microwave power is 1800 W.
基金Sponsored bythe Ministerial Level Advanced Research Foundation (K130306068)
文摘Based on miniaturized components’ characteristics, the method of assembling miniaturized gear and shaft together with corresponding calculating model of the interference amount are proposed. On the basis of main effecting factors analysis on the gear and shaft assembling interference amount, calculating formula including all factors effective on the interference amount necessary for reliable system running was built up. The methods of reverse calculating theoretical model was used to build up the equivalent simulation model of the theoretical one, together with simulation verification and case study for calculating formula. The results show that the cold assembling method is applicable for miniaturized gear and shaft, but in the assembling process, the interference amount compensating the shape error of contacting surfaces takes a large proportion, which is the main cause of stress variance on contacting surfaces.
基金supported by the Key Project of Natural Science Foundation of China under Grant No. 60537040the Natural Science Foundation Project of CQ CSTC under Grant No. 2007BB3125
文摘This paper presents a novel miniaturized fiber-optic Fabry-Peort interferometer (FPI) for highly sensitive refractive index measurement. This device was tested for the refractive indices of various liquids including acetone and ethanol at room temperature. The sensitivity for measurement of refractive index change of ethanol is 1138 nm/RIU at the wavelength of 1550 nm. In addition, the sensor fabrication is simple including only cleaving, splicing, and etching. The signal is stable with high visibility. Therefore, it provides a valuable tool in biological and chemical applications.
基金supported by National Natural Science Foundation of China(Grant Nos.12205019,12147144 and 11975036).The support from State Key Laboratory of Nuclear Physics and Technology,Peking University is appreciated.
文摘The generation of plasma in a microwave ion source involves confining electrons using a static magnetic field and energizing them with an electromagnetic field that transmitted into the plasma chamber.However,according to electromagnetics theory,there is always a cut-off size in circular wave guides for a given frequency.For a 2.45 GHz microwave,this dimension is 72 mm,which should theoretically prevent transmission of the microwave into the discharge chamber and no plasma can be generated.Since 2006 Peking University(PKU)has successfully developed a series of permanent magnet 2.45 GHz microwave ion sources(PKU PMECRs)with a discharge chamber less than 50 mm,capable of delivering tens of mA beams for accelerators.To explain this anomalous phenomenon,a hybrid discharge heating(HDH)mode that combines surface wave plasma and electron cyclotron heating has been proposed.This HDH mode not only successfully explains PKU PMECRs,but also predicts that the optimized inner diameter of the plasma chamber is 24 mm,which is confirmed by experiments involving different liners in the miniaturized microwave ion source.
基金supported by the National Natural Science Foundation of China(Grant Nos.22275092,52102107 and 52372084)the Fundamental Research Funds for the Central Universities(Grant No.30923010920)。
文摘Energetic Semiconductor bridge(ESCB)based on reactive multilayered films(RMFs)has a promising application in the miniature and intelligence of initiator and pyrotechnics device.Understanding the ignition enhancement mechanism of RMFs on semiconductor bridge(SCB)during the ignition process is crucial for the engineering and practical application of advanced initiator and pyrotechnics devices.In this study,a one-dimensional(1D)gas-solid two-phase flow ignition model was established to study the ignition process of ESCB to charge particles based on the reactivity of Al/MoO_(3) RMFs.In order to fully consider the coupled exothermic between the RMFs and the SCB plasma during the ignition process,the heat release of chemical reaction in RMFs was used as an internal heat source in this model.It is found that the exothermal reaction in RMFs improved the ignition performance of SCB.In the process of plasma rapid condensation with heat release,the product of RMFs enhanced the heat transfer process between the gas phase and the solid charge particle,which accelerated the expansion of hot plasma,and heated the solid charge particle as well as gas phase region with low temperature.In addition,it made up for pressure loss in the gas phase.During the plasma dissipation process,the exothermal chemical reaction in RMFs acted as the main heating source to heat the charge particle,making the surface temperature of the charge particle,gas pressure,and gas temperature rise continuously.This result may yield significant advantages in providing a universal ignition model for miniaturized ignition devices.
文摘空射诱饵弹(miniature air launched decoy,MALD)可诱骗地面防空雷达开机,消耗防空弹药,降低地面防空装备作战效能,提升空中编队突防能力。在梳理空射诱饵弹发展概况基础上,分析空射诱饵弹目标特性,构建典型作战运用场景,开展MALD对制导雷达探测跟踪性能和拦截效能影响分析,采用理论分析和动态仿真的方法研究了空射诱饵弹实施远距离欺骗、抵近干扰对制导雷达探测跟踪性能的影响,采用排队论方法分析MALD对空中编队突防效能的影响。研究结论可为空射诱饵弹战术运用提供参考。
