In this paper,a linear optimization method(LOM)for the design of terahertz circuits is presented,aimed at enhancing the simulation efficacy and reducing the time of the circuit design workflow.This method enables the ...In this paper,a linear optimization method(LOM)for the design of terahertz circuits is presented,aimed at enhancing the simulation efficacy and reducing the time of the circuit design workflow.This method enables the rapid determination of optimal embedding impedance for diodes across a specific bandwidth to achieve maximum efficiency through harmonic balance simulations.By optimizing the linear matching circuit with the optimal embedding impedance,the method effectively segregates the simulation of the linear segments from the nonlinear segments in the frequency multiplier circuit,substantially improving the speed of simulations.The design of on-chip linear matching circuits adopts a modular circuit design strategy,incorporating fixed load resistors to simplify the matching challenge.Utilizing this approach,a 340 GHz frequency doubler was developed and measured.The results demonstrate that,across a bandwidth of 330 GHz to 342 GHz,the efficiency of the doubler remains above 10%,with an input power ranging from 98 mW to 141mW and an output power exceeding 13 mW.Notably,at an input power of 141 mW,a peak output power of 21.8 mW was achieved at 334 GHz,corresponding to an efficiency of 15.8%.展开更多
In order to improve the quality of 3D printed raspberry preserves after post-processing,microwave ovens combining infrared and microwave methods were utilized.The effects of infrared heating temperature,infrared heati...In order to improve the quality of 3D printed raspberry preserves after post-processing,microwave ovens combining infrared and microwave methods were utilized.The effects of infrared heating temperature,infrared heating time,microwave power,microwave heating time on the center temperature,moisture content,the chroma(C*),the total color difference(ΔE*),shape fidelity,hardness,and the total anthocyanin content of 3D printed raspberry preserves were analyzed by response surface method(RSM).The results showed that under combining with the two methods,infrared heating improved the fidelity and quality degradation of printed products,while microwave heating enhanced the efficiency of infrared heating.Infrared-microwave combination cooking could maintain relatively stable color appearance and shape of 3D printed raspberry preserves.The AHP–CRITIC hybrid weighting method combined with the response surface test to determine the comprehensive weights of the evaluation indicators optimized the process parameters,and the optimal process parameters were obtained:infrared heating temperature of 190℃,infrared heating time of 10 min and 30 s,microwave power of 300 W,and microwave heating time of 2 min and 6 s.The 3D printed raspberry cooking methods obtained under the optimal conditions seldom had color variation,porous structure,uniform texture,and high shape fidelity,which retained the characteristics of personalized manufacturing by 3D printing.This study could provide a reference for the postprocessing and quality control of 3D cooking methods.展开更多
在强光照射下,CdS量子点易发生光腐蚀现象,通过金属掺杂和复合的方式可以提高CdS的光催化性能和光稳定性。采用水热法合成了Zn掺杂CdS/g-C_(3)N_(4)复合纳米材料(Zn-CdS/g-C_(3)N_(4))。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、...在强光照射下,CdS量子点易发生光腐蚀现象,通过金属掺杂和复合的方式可以提高CdS的光催化性能和光稳定性。采用水热法合成了Zn掺杂CdS/g-C_(3)N_(4)复合纳米材料(Zn-CdS/g-C_(3)N_(4))。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和傅里叶变换红外光谱(FT-IR)等手段对Zn-CdS/g-C_(3)N_(4)复合材料的形貌、结构和组成等进行了表征。结果表明,Zn-CdS纳米颗粒附着在g-C_(3)N_(4)表面上,从而形成Zn-CdS/g-C_(3)N_(4)复合材料,且复合后材料带隙减小,光生电子-空穴复合率降低。在500 W Xe灯照射下,研究了Zn-CdS/g-C_(3)N_(4)对罗丹明B(RhB)的光催化降解性能。在最优条件下,光照40 min后,所制备的Zn-CdS/g-C_(3)N_(4)对RhB的光催化降解效率达99%。此外,所合成的Zn-CdS/g-C_(3)N_(4)复合材料光稳定性较高、可再生性好。这归因于Zn和Cd的协同作用以及与g-C_(3)N_(4)的复合,促进了光生载流子的分离和转移。展开更多
The CaCu3Ti4O12 xerogels, powders and ceramics were prepared through the sol-gel method using two kinds of organic acid （decanoic acid and decanedioic acid）. The xerogels, powders and ceramics were characterized by ...The CaCu3Ti4O12 xerogels, powders and ceramics were prepared through the sol-gel method using two kinds of organic acid （decanoic acid and decanedioic acid）. The xerogels, powders and ceramics were characterized by the methods of TG-DTG, FT-IR, XRD, SEM and TEM. The dielectric properties of the ceramics were also measured. The results indicated that the powders calcined at 850 ℃ for 2 h are both nanometer scale particles. After sintering, the ceramics mainly consist of the CaCu3Ti4O12 phase. Compared with the powders prepared using monoacid, the particle size of the powders prepared using diacid obviously increases, and the grain size, the relative density and the whole permittivity of the ceramics increase as well. Specially, the ceramic prepared using decanedioic acid has higher relative density （97.3%）, dielectric constant （316 808） and lower dielectric loss （0.242 5） at 30 ℃ （10 kIaz）展开更多
Ammonium aluminum carbonate hydroxide (AACH) precursor was synthesized by the precipitation reaction of aluminum sulfate and ammonium carbonate. Then the precursor was dealt with five drying methods including ordinary...Ammonium aluminum carbonate hydroxide (AACH) precursor was synthesized by the precipitation reaction of aluminum sulfate and ammonium carbonate. Then the precursor was dealt with five drying methods including ordinary drying, alcohol exchange, vacuum freeze-drying, glycol distillation, n-butanol azeotropic distillation respectively and calcined at 1 200 ℃ for 2 h to get α-Al2O3. The effects of drying methods on preparation of nanometer α-Al2O3 were discussed, and the optimal drying method was confirmed. The structural properties of powders were characterized by XRD, SEM and BET measurements. The results show that vacuum freeze-drying, glycol distillation and n-butanol azeotropic distillation can prevent the powders from aggregating, and among them the n-butanol azeotropic distillation is the best method. The nanometer α-Al2O3 powder with non-aggregation can be manufactured using n-butanol azeotropic distillation and the average particle size is about 40 nm.展开更多
Highly pure active γ-Al2O3 nanoparticles were synthesized from aluminum nitrate and ammonium carbonate with a little surfactant by chemical precipitation method. The factors affecting the synthesis process were studi...Highly pure active γ-Al2O3 nanoparticles were synthesized from aluminum nitrate and ammonium carbonate with a little surfactant by chemical precipitation method. The factors affecting the synthesis process were studied. The properties of γ-Al2O3 nanoparticles were characterized by DTA, XRD, BET, TEM, laser granularity analysis and impurity content analysis. The results show that the amorphous precursor AI（OH）3 sols are produced by using 0.1 mol/L Al（NO3）3·9H2O and 0.16 mol/L （NH4）2CO3·H2O reaction solutions, according to the volume ratio 1.33, adding 0.024%（volume fraction） surfactant PEG600, and reacting at 40℃, 1000 r/min stirring rate for 15min. Then, after stabilizing for 24 h, the precursors were extracted and filtrated by vacuum, washed thoroughly with deionized water and dehydrated ethanol, dried in vacuum at 80℃ for 8h, final calcined at 800℃ for 1h in the air, and high purity active γ-Al2O3 nanoparticles can be prepared with cubic in crystal system, OH^7-FD3M in space group, about 9 nm in crystal grain size, about 20 nm in particle size and uniform size distribution, 131.35 m^2/g in BET specific surface area, 7 - 11 nm in pore diameter, and not lower than 99.93% in purity.展开更多
Optimization of design features of reinforced sheet is investigated. Initially, equations governing composite structures are extracted based on Kirchhoff sheet model under bending using Hamilton's principal. Then,...Optimization of design features of reinforced sheet is investigated. Initially, equations governing composite structures are extracted based on Kirchhoff sheet model under bending using Hamilton's principal. Then, design parameters for the composite structure are extracted with simple supportive boundary conditions from proposed solution. Next, optimization is achieved by determining dimensions of a reinforced sheet specimen. Weight optimization of reinforced sheet structure has been obtained based on variations in thickness and number of longitudinal and transverse reinforcements. Buckling static characteristic is utilized in optimization process. To solve the extracted equations, semi-analytical method of CS-DSG3 has been applied. Results are presented in graphs that show variation of design parameters by changing the geometric parameters. ABAQUS software has been used for design verification. The results show that an increase in thickness of 3 mm skip value tends to be zero. Also, there is a change in the amount of deflection for sheets with a minimum thickness of 3 mm by increasing the number of longitudinal and transverse reinforcement. There is a good agreement between the numerical method of finite elements and the method X-FEM-DSG3.展开更多
基金Supported by the Beijing Municipal Science&Technology Commission(Z211100004421012),the Key Reaserch and Development Pro⁃gram of China(2022YFF0605902)。
文摘In this paper,a linear optimization method(LOM)for the design of terahertz circuits is presented,aimed at enhancing the simulation efficacy and reducing the time of the circuit design workflow.This method enables the rapid determination of optimal embedding impedance for diodes across a specific bandwidth to achieve maximum efficiency through harmonic balance simulations.By optimizing the linear matching circuit with the optimal embedding impedance,the method effectively segregates the simulation of the linear segments from the nonlinear segments in the frequency multiplier circuit,substantially improving the speed of simulations.The design of on-chip linear matching circuits adopts a modular circuit design strategy,incorporating fixed load resistors to simplify the matching challenge.Utilizing this approach,a 340 GHz frequency doubler was developed and measured.The results demonstrate that,across a bandwidth of 330 GHz to 342 GHz,the efficiency of the doubler remains above 10%,with an input power ranging from 98 mW to 141mW and an output power exceeding 13 mW.Notably,at an input power of 141 mW,a peak output power of 21.8 mW was achieved at 334 GHz,corresponding to an efficiency of 15.8%.
基金Supported by the National Natural Science Foundation of China(32072352)。
文摘In order to improve the quality of 3D printed raspberry preserves after post-processing,microwave ovens combining infrared and microwave methods were utilized.The effects of infrared heating temperature,infrared heating time,microwave power,microwave heating time on the center temperature,moisture content,the chroma(C*),the total color difference(ΔE*),shape fidelity,hardness,and the total anthocyanin content of 3D printed raspberry preserves were analyzed by response surface method(RSM).The results showed that under combining with the two methods,infrared heating improved the fidelity and quality degradation of printed products,while microwave heating enhanced the efficiency of infrared heating.Infrared-microwave combination cooking could maintain relatively stable color appearance and shape of 3D printed raspberry preserves.The AHP–CRITIC hybrid weighting method combined with the response surface test to determine the comprehensive weights of the evaluation indicators optimized the process parameters,and the optimal process parameters were obtained:infrared heating temperature of 190℃,infrared heating time of 10 min and 30 s,microwave power of 300 W,and microwave heating time of 2 min and 6 s.The 3D printed raspberry cooking methods obtained under the optimal conditions seldom had color variation,porous structure,uniform texture,and high shape fidelity,which retained the characteristics of personalized manufacturing by 3D printing.This study could provide a reference for the postprocessing and quality control of 3D cooking methods.
文摘在强光照射下,CdS量子点易发生光腐蚀现象,通过金属掺杂和复合的方式可以提高CdS的光催化性能和光稳定性。采用水热法合成了Zn掺杂CdS/g-C_(3)N_(4)复合纳米材料(Zn-CdS/g-C_(3)N_(4))。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和傅里叶变换红外光谱(FT-IR)等手段对Zn-CdS/g-C_(3)N_(4)复合材料的形貌、结构和组成等进行了表征。结果表明,Zn-CdS纳米颗粒附着在g-C_(3)N_(4)表面上,从而形成Zn-CdS/g-C_(3)N_(4)复合材料,且复合后材料带隙减小,光生电子-空穴复合率降低。在500 W Xe灯照射下,研究了Zn-CdS/g-C_(3)N_(4)对罗丹明B(RhB)的光催化降解性能。在最优条件下,光照40 min后,所制备的Zn-CdS/g-C_(3)N_(4)对RhB的光催化降解效率达99%。此外,所合成的Zn-CdS/g-C_(3)N_(4)复合材料光稳定性较高、可再生性好。这归因于Zn和Cd的协同作用以及与g-C_(3)N_(4)的复合,促进了光生载流子的分离和转移。
基金Projects(CC20120031,CC20110048)supported by Changzhou Science and Technology Innovation Project,China
文摘The CaCu3Ti4O12 xerogels, powders and ceramics were prepared through the sol-gel method using two kinds of organic acid （decanoic acid and decanedioic acid）. The xerogels, powders and ceramics were characterized by the methods of TG-DTG, FT-IR, XRD, SEM and TEM. The dielectric properties of the ceramics were also measured. The results indicated that the powders calcined at 850 ℃ for 2 h are both nanometer scale particles. After sintering, the ceramics mainly consist of the CaCu3Ti4O12 phase. Compared with the powders prepared using monoacid, the particle size of the powders prepared using diacid obviously increases, and the grain size, the relative density and the whole permittivity of the ceramics increase as well. Specially, the ceramic prepared using decanedioic acid has higher relative density （97.3%）, dielectric constant （316 808） and lower dielectric loss （0.242 5） at 30 ℃ （10 kIaz）
基金Project (5JJ30103) supported by the Natural Science Foundation of Hunan Province, China
文摘Ammonium aluminum carbonate hydroxide (AACH) precursor was synthesized by the precipitation reaction of aluminum sulfate and ammonium carbonate. Then the precursor was dealt with five drying methods including ordinary drying, alcohol exchange, vacuum freeze-drying, glycol distillation, n-butanol azeotropic distillation respectively and calcined at 1 200 ℃ for 2 h to get α-Al2O3. The effects of drying methods on preparation of nanometer α-Al2O3 were discussed, and the optimal drying method was confirmed. The structural properties of powders were characterized by XRD, SEM and BET measurements. The results show that vacuum freeze-drying, glycol distillation and n-butanol azeotropic distillation can prevent the powders from aggregating, and among them the n-butanol azeotropic distillation is the best method. The nanometer α-Al2O3 powder with non-aggregation can be manufactured using n-butanol azeotropic distillation and the average particle size is about 40 nm.
文摘Highly pure active γ-Al2O3 nanoparticles were synthesized from aluminum nitrate and ammonium carbonate with a little surfactant by chemical precipitation method. The factors affecting the synthesis process were studied. The properties of γ-Al2O3 nanoparticles were characterized by DTA, XRD, BET, TEM, laser granularity analysis and impurity content analysis. The results show that the amorphous precursor AI（OH）3 sols are produced by using 0.1 mol/L Al（NO3）3·9H2O and 0.16 mol/L （NH4）2CO3·H2O reaction solutions, according to the volume ratio 1.33, adding 0.024%（volume fraction） surfactant PEG600, and reacting at 40℃, 1000 r/min stirring rate for 15min. Then, after stabilizing for 24 h, the precursors were extracted and filtrated by vacuum, washed thoroughly with deionized water and dehydrated ethanol, dried in vacuum at 80℃ for 8h, final calcined at 800℃ for 1h in the air, and high purity active γ-Al2O3 nanoparticles can be prepared with cubic in crystal system, OH^7-FD3M in space group, about 9 nm in crystal grain size, about 20 nm in particle size and uniform size distribution, 131.35 m^2/g in BET specific surface area, 7 - 11 nm in pore diameter, and not lower than 99.93% in purity.
文摘Optimization of design features of reinforced sheet is investigated. Initially, equations governing composite structures are extracted based on Kirchhoff sheet model under bending using Hamilton's principal. Then, design parameters for the composite structure are extracted with simple supportive boundary conditions from proposed solution. Next, optimization is achieved by determining dimensions of a reinforced sheet specimen. Weight optimization of reinforced sheet structure has been obtained based on variations in thickness and number of longitudinal and transverse reinforcements. Buckling static characteristic is utilized in optimization process. To solve the extracted equations, semi-analytical method of CS-DSG3 has been applied. Results are presented in graphs that show variation of design parameters by changing the geometric parameters. ABAQUS software has been used for design verification. The results show that an increase in thickness of 3 mm skip value tends to be zero. Also, there is a change in the amount of deflection for sheets with a minimum thickness of 3 mm by increasing the number of longitudinal and transverse reinforcement. There is a good agreement between the numerical method of finite elements and the method X-FEM-DSG3.
