Synthesis of Au Nanoparticles Functionalized 1D α-MoO3 Nanobelts and Their Gas Sensing Properties

Liwei Wang,Shaopeng Wang,Hao Fu,Yinghui Wang,Kefu Yu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.10

A novel sensor material of Au nanoparticles (NPs) functionalized 1D α-MoO3 nanobelts (NBs) was fabricated by a facile lysine-assisted approach. The obtained Au/α-MoO3 product was characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive X-ray (EDX), and X-ray photoelectron spectra (XPS). Then, in order to investigate the gas sensing performances of our samples, a comparative gas sensing study was carried out on both the α-MoO3 NBs before and after Au NPs decoration by using ethanol vapor as the molecular probe. The results turned out that, after the functionalization of Au NPs, the sensor exhibited improved gas-sensing characteristics than the pure α-MoO3, such as response and recovery time, optimal operating temperature (OT) and excellent selectivity. Take for example 200 ppm of ethanol, the response/ recovery times were 34 s/43 s and 5.7 s/10.5 s, respectively, while the optimal operating temperature (OT) was lower to 200 ℃ rather than 250 ℃. Besides, the functionalized sensor showed a higher response to ethanol at 200 ℃, and response was 1.6 times higher than the pure MoO3. The mechanism of such improved sensing properties was interpreted, which might be attributed to the spillover effect of Au NPs and the electronic metal-support interaction.

Multilinear Calderon-Zygmund operators and their commutators on central Morrey spaces with variable exponent

Liwei Wang 대한수학회 2020 대한수학회보 Vol.57 No.6

In this paper, we establish the boundedness of the $m$-linear Calder\'{o}n-Zygmund operators on product of central Morrey spaces with variable exponent. The corresponding boundedness properties of their commutators with $\lambda$-central {\rm BMO} symbols are also considered. Finally, we prove that the multilinear commutators of Calder\'{o}n-Zygmund singular integrals introduced by P\'{e}rez and Trujillo-Gonz\'{a}lez are bounded on central Morrey spaces with variable exponent. Our results improve and generalize some previous classical results to the variable exponent setting.

BOUNDEDNESS OF THE COMMUTATOR OF THE INTRINSIC SQUARE FUNCTION IN VARIABLE EXPONENT SPACES

Wang, Liwei Korean Mathematical Society 2018 대한수학회지 Vol.55 No.4

In this paper, we show that the commutator of the intrinsic square function with BMO symbols is bounded on the variable exponent Lebesgue spaces $L^{p({\cdot})}({\mathbb{R}}^n)$ applying a generalization of the classical Rubio de Francia extrapolation. As a consequence we further establish its boundedness on the variable exponent Morrey spaces $\mathcal{M_{p({\cdot}),u}$, Morrey-Herz spaces $M{\dot{K}}^{{\alpha}({\cdot}),{\lambda}}_{q,p({\cdot})}({\mathbb{R}}^n)$ and Herz type Hardy spaces $H{\dot{K}}^{{\alpha}({\cdot}),q}_{p({\cdot})}({\mathbb{R}}^n)$, where the exponents ${\alpha}({\cdot})$ and $p({\cdot})$ are variable. Observe that, even when ${\alpha}({\cdot}){\equiv}{\alpha}$ is constant, the corresponding main results are completely new.

Boundedness of the commutator of the intrinsic square function in variable exponent spaces

Liwei Wang 대한수학회 2018 대한수학회지 Vol.55 No.4

In this paper, we show that the commutator of the intrinsic square function with {\rm BMO} symbols is bounded on the variable exponent Lebesgue spaces $L^{p(\cdot)}(\mathbb{R}^n)$ applying a generalization of the classical Rubio de Francia extrapolation. As a consequence we further establish its boundedness on the variable exponent Morrey spaces $\mathcal{M}_{p(\cdot), u}$, Morrey-Herz spaces $M\dot{K}_{q, p(\cdot)}^{\alpha(\cdot), \lambda}({\mathbb { R}}^n)$ and Herz type Hardy spaces $H\dot{K}_{p(\cdot)}^{\alpha(\cdot), q}({\mathbb { R}}^n)$, where the exponents $\alpha(\cdot)$ and $p(\cdot)$ are variable. Observe that, even when $\alpha(\cdot)\equiv \alpha$ is constant, the corresponding main results are completely new.

FEM Simulation and Test Verification of PD Ultrasonic Signal Propagation in a Power Transformer Model

Zan Wang,Chaofei Gao,Liwei Zheng,Jikun Ren,Wei Wang,Yushuai Zhang,Shijie Han 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.1

Ultrasonic signals will be generated when partial discharge occurs in internal insulation faults in large oil immersed power transformers: because the ultrasonic signal has strong anti-interference ability and has no direct electromagnetic contact with the equipment, it is widely used in transformer fault detection and positioning. In this paper, the fi nite element method (FEM) is used to simulate the ultrasonic signal in a 35 kV power transformer. The infl uence of transformer case on ultrasonic signal propagation is considered, and the propagation law of the ultrasonic signal inside the transformer is obtained. Fabry–Pérot (F–P) fi bre acoustic sensors with a centre frequency of 28 kHz were fabricated. A partial discharge detection test was carried out in a 35 kV transformer winding model using the F–P sensors. The test results show that the ultrasonic waveform detected by the F–P sensors are in good agreement with the simulation results, and the propagation of the ultrasonic wave inside the transformer is verifi ed. It lays a foundation for detecting and locating PDs in power transformer by F–P acoustic sensors.

PERFORMANCE IMPROVEMENT OF AN ADSORPTION CHILLER USING COMPOSITE ADSORBENT, SILICA GEL IMPREGNATED WITH LITHIUM CHLORIDE, PAIRED WITH METHANOL AS THE ADSORBATE

FRED T. ISHUGAH, RUZHU WANG,LIWEI WANG,ZISHENG LU 대한설비공학회 2014 International Journal Of Air-Conditioning and Refr Vol.22 No.2

This study aimed at analyzing different operation strategies to improve the performance of anew type adsorption chiller employing a novel composite adsorbent, silica gel impregnated withlithium chloride, paired with methanol as the adsorbate. The chiller's experimental test resultsshowed an average Specific. Cooling Power (SCP) and Coeffient of Performance (COP) of286 W/kg and 0.48, respectively. This was when the average hot water inlet temperature,cooling water inlet temperature, and chilled water inlet temperature were 83C, 26C and 15C,respectively. In addition, the corresponding mass flow rates were 0.22, 0.39 and 0.09 kg/s, respectively. Despite the fact that the average SCP and COP, were rather satisfactory, analysis ofexperimental results conducted with different cycle times, inlet hot water temperatures, and hotwater flow rates showed that a much better performance could be achieved. Experimentalresults indicated the following: (1) the COP increased while the SCP decreased with increasedcycle time, (2) both the COP and the SCP increased with increase in heat and mass recoverytime to an optimal time then started to decrease as heat and mass recovery time increasedbeyond the optimal time, (3) both the cooling power and COP generally increased with increasein inlet hot water temperature at a relatively higher value from 60C to about 90C beyondwhich the incremental value started diminishing, and, (4) increase in mass flow rates producedhigher cooling power with decreased COP while decrease in mass flow rates of hot water producedlower cooling power with increased COP. This paper therefore recommends an adsorption/desorption time, heat and mass recovery time, inlet hot water temperature, and hot watermass flow rate of 780 s, 60 s, 83C, and 0.22 kg/s as appropriate to give the best chiller performancefor refrigeration.

Characteristics and Optimization of New Combined Magnetic Pole Negative-Salient Permanent Magnet Motor

Wang Wenqiang,Shi Liwei,Qiao Zhiwei,Zhu Yingjie,Ding Hongshan 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3

With a wide speed range, high overload capacity and preventing permanent magnet demagnetization, negative-salient permanent magnet motors have a wide range of applications in the feld of electric vehicles. In view of the multiple operating conditions of the electric vehicle drive motor, this paper proposes a new type of combined magnetic pole negative-salient permanent magnet motor considering the driving conditions. Firstly, the optimization parameters of the motors are determined according to the analysis of the mathematical model. The design parameters are layered by the comprehensive sensitivity analysis, and the response surface Box-Behnken Design method and multi-objective genetic algorithm-II are used for optimization. Then, the electromagnetic performance of the proposed motor and the traditional interior permanent magnet motors are compared and analyzed through the fnite element simulation. Finally, a prototype is manufactured and the rationality of the proposed motor structure is verifed by experiments.

Improving performance of medical image alignment through super-resolution

Liwei Deng,Yuanzhi Zhang,Jing Wang,Sijuan Huang,Xin Yang 대한의용생체공학회 2023 Biomedical Engineering Letters (BMEL) Vol.13 No.3

Medical image alignment is an important tool for tracking patient conditions, but the quality of alignment is influenced bythe effectiveness of low-dose Cone-beam CT (CBCT) imaging and patient characteristics. To address these two issues, wepropose an unsupervised alignment method that incorporates a preprocessing super-resolution process. We constructed themodel based on a private clinical dataset and validated the enhancement of the super-resolution on alignment using clinicaland public data. Through all three experiments, we demonstrate that higher resolution data yields better results in the alignmentprocess. To fully constrain similarity and structure, a new loss function is proposed; Pearson correlation coefficientcombined with regional mutual information. In all test samples, the newly proposed loss function obtains higher resultsthan the common loss function and improve alignment accuracy. Subsequent experiments verified that, combined with thenewly proposed loss function, the super-resolution processed data boosts alignment, can reaching up to 9.58%. Moreover,this boost is not limited to a single model, but is effective in different alignment models. These experiments demonstratethat the unsupervised alignment method with super-resolution preprocessing proposed in this study effectively improvedalignment and plays an important role in tracking different patient conditions over time.

Analysis of Science and Engineering Graduates Employment Ability Factors based on FAHP

Liwei Gu,Yubin Wang,Yuhong Zhang 보안공학연구지원센터(IJUNESST) 2014 International Journal of u- and e- Service, Scienc Vol.7 No.4

Experimental Study of the band-pass Filter and Slow-wave Effect in a MDM channel Based on a Magnetic Plasmonic Analogue of EIT

Wusong Wang,Liwei Zhang,Liqing Shang,Yewen Zhang 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.9

In connection with an analogue of electromagnetically-induced transparency (EIT), this paper studied experimentally the tunable band-pass filter and tunable slow-wave effect of MDM (μ-negative materials/double positive materials/μ-negative materials) magnetic plasmonic channel. The results of simulations and experiments show that an evident electromagnetically-induced transparency phenomenon appears in this channel with double-side resonators, which can be used to realize simultaneous the band-pass filter and the slow-wave effect. The band-pass filter’s center frequency is founded to be determined by the size of the side resonator, the resonator direction and the effective permeability of μ-negative (MNG) metamaterials. The bandwidth can be adjusted by detuning of the two resonator frequencies, the band size of the band-pass filter depends on the number of the resonators, Thus, the band-pass filter characteristics of the MDM waveguide can be tuned by changing the resonator parameters, the resonator direction and the effective permeability of the MNG materials. Moreover, the MDM structure can also be utilized to obtain a tunable slow-wave effect (such as an adjustable frequency, a slow-down factor, and even a muti-band slow wave) based on EIT. The experimental results are in good agreement with the simulation results.