A Tower-Shaped Three-Dimensional Piezoelectric Energy Harvester for Low-Level and Low-Frequency Vibration

Xiaoxiang Wei,Haibo Zhao,Junjie Yu,Yiming Zhong,Yanlin Liao,Shiwei Shi,Peihong Wang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.5

The multiple forms of vibration exist in an ambient environment diffusely and already become a considerable object for energy harvesting. However, how to effectively extract low-level, low-frequency, and multi-directional vibration from the ambient environment is becoming a key issue in the field of energy harvesting. To solve this issue, a tower-shaped piezoelectric vibration energy harvester (TS-PVEH) is reported. Finite element simulation indicates that TS-PVEH works in two fundamental modes, i.e., its in-plane and out-of-plane vibration modes. Meanwhile, simulation results show that the natural frequency of TS-PVEH is 3.39 Hz, 3.40 Hz, and 11.50 Hz, respectively; and the experiments also verified that. By virtue of the tower structure of TS-PVEH, the device is pretty sensitive to three-dimensional vibration. At a low level of acceleration 1 m/s 2 , the maximum load power of TS-PVEH is 65.8 μW in out-of-plane mode and 17.2 μW in in-plane mode, respectively. Furthermore, the effects of the PVDF connection mode on the output performance of TS-PVEH were studied in detail, and comparative experimental results show that a reasonable connection of PVDF can improve energy harvesting efficiency. The proposed TS-PVEH is expected to be used to scavenge energy from multi-dimensional, low-level, and low-frequency vibrations that present in an ambient environment.

A construction of QC-LDPC codes using Golomb rulers generated from sonar sequences

Xiaoxiang Jin(김소상),Sangwon Chae(채상원),Hong-Yeop Song(송홍엽) 한국통신학회 2023 한국통신학회 학술대회논문집 Vol.2023 No.6

Modelling of flange-stud-slab interactions and numerical study on bottom-flange-bolted composite-beam connections

Xiaoxiang Wang,Yu-jie Yu,Lizhong Jiang,Zhi-wu Yu 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.47 No.2

The composite beam connections often encountered fracture failure in the welded bottom flange joint, and a bottom flange bolted connection has been proposed to increase the deformation ability of the bottom flange joint. The seismic performance of the bottom flange bolted composite beam connection was suffered from both the composite action of concrete slab and the asymmetric load transfer mechanisms between top and bottom beam flange joints. Thus, this paper presents a comprehensive numerical study on the working mechanism of the bottom flange bolted composite beam connections. Three available modelling methods and a new modelling method on the flange-stud-slab interactions were compared. The efficient numerical modeling method was selected and then applied to the parametric study. The influence of the composite slab, the bottom flange bolts, the shear composite ratio and the web hole shape on the seismic performance of the bottom flange bolted composite beam connections were investigated. A hogging strength calculation method was then proposed based on numerical results.

Heterogeneous amino acid-based tungstophosphoric acids as efficient and recyclable catalysts for selective oxidation of benzyl alcohol

Xiaoxiang Han,Yingying Kuang,Chunhua Xiong,Xiujuan Tang,Qing Chen,Chin-Te Hung,Li-Li Liu,Shang-Bin Liu 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.7

A series of organic-inorganic composite catalysts, prepared by modifying tungstophosphoric acid (TPA; H3PW12O40) with different amino acids such as phenylalanine (Phe), alanine (Ala), and glycine (Gly) were synthesized. The physicochemical and acidic properties of these (MH)xH3−xPW12O40 (M=Phe, Ala, and Gly; x=1-3) composite materials were characterized by a variety of different analytical and spectroscopic techniques, namely TGA, XRD, FTIR, XPS, and NMR, and exploited as heterogeneous catalysts for selective oxidation of benzyl alcohol (BzOH) with hydrogen peroxide (H2O2). Among them, the [PheH]H2PW12O40 catalyst exhibited the best oxidative activity with an excellent BzOH conversion of 99.0% and a desirable benzaldehyde (BzH) selectivity of 99.6%. Further kinetic studies and model analysis by response surface methodology (RSM) revealed that the oxidation of BzOH with H2O2 follows a second-order reaction with an activation energy of 56.7 kJ·mol−1 under optimized experimental variables: BzOH/H2O2 molar ratio=1 : 1.5mol/mol, amount of catalyst=6.1 wt%, reaction time (x3)=3.8 h, and amount of water (x4)=30.2mL.

Transesterification of soybean oil to biodiesel by tin-based Brønsted-Lewis acidic ionic liquid catalysts

Xiaoxiang Han,Shang-Bin Liu,Wei Yan,Chin-Te Hung,Yanfei He,Pei-Hao Wu,Li-Li Liu,Shing-Jong Huang 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.7

A series of Brønsted-Lewis acidic ionic liquid (BLAIL) catalysts consisting of sulfonated ionic liquid [SO3H-pmim]Cl and Sn(II) chloride have been synthesized and exploited for catalytic transesterification of soybean oil with methanol to biodiesel. The structural and chemical properties of these [SO3H-pmim]Cl-xSnCl2 (x=0-0.8) catalysts were characterized by different analytical and spectroscopic techniques, such as FT-IR, TGA, and NMR. In particular, their acid properties were studied by solid-state 31P NMR using trimethylphosphine oxide as the probe molecule. The BLAIL catalysts were found highly efficient for transesterification reaction due to the introduction of Lewis acidity by SnCl2 in the initially Brønsted acidic [SO3H-pmim]Cl catalyst. The effects of three independent process variables on biodiesel yield were optimized by response surface methodology (RSM). Consequently, an excellent biodiesel yield of 98.6% was achieved under optimized reaction conditions over the BLAIL catalyst with SnCl2 loading (x) of 0.7.

Pb(II) ion adsorption by biomass-based carbonaceous fiber modified by the integrated oxidation and vulcanization

Xiaoxiang Jiang,Dekui Shen 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.10

Biomass-based activated carbonaceous fiber (ACF) was modified by nitric-acid oxidation under microwave heating (ACF-O) and then further treated by thioglycolic acid (ACF-S) to prepare carbon materials with high capability for the removal of Pb(II) ions. The physico-chemical properties of the original and modified ACF samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Zeta potential, Boehm titration, BET, Raman spectrum and X-ray photoelectron spectroscopy (XPS). It was found that modification treatments damage the pore and graphite crystalline structure of ACF, while the micropore structure is protected and extra oxygen-containing surface functional groups are grafted on its surface. The adsorption performance of the original and the modified ACF samples affected by adsorption conditions regarding to Pb(II) ion strength (10mg/L- 105mg/L), contact time (10min-120 min), pH value (2.5-6.5), and solvent temperature (15 oC-45 oC) was investigated through batch experiments. Compared to the maximum Pb(II) ion adsorption capacity of 75.24mg/g by ACF sample, the value was substantially improved by the integrated modification method (193.42mg/g for ACF-O and 209.21mg/g for ACF-S sample). The Biot number determined from the homogeneous surface diffusion model (HSDM) was between 1 and 100 for the original and modified ACF samples, suggesting that the adsorption process of Pb(II) ions is limited by both the surface diffusion and film mass transfer.

A Study of Segmental and Syllabic Intervals of Canonical Babbling and Early Speech*

( Xiaoxiang Chen ),( Yunnan Xiao ) 경희대학교 비교문화연구소 2012 비교문화연구 Vol.28 No.-

Interval or duration of segments, syllables, words and phrases is an important acoustic feature which influences the naturalness of speech. A number of cross-sectional studies regarding acoustic characteristics of children`s speech development found that intervals of segments, syllables, words and phrases tend to change with the growing age. One hypothesis assumed that decreases in intervals would be greater when children were younger and smaller decreases in intervals when older (Thelen ,1991 ), it has been supported by quite a number of researches on the basis of cross-sectional studies (Tingley & Allen, 1975; Kent & Forner, 1980; Chermark & Schnerderman, 1986), but the other bypothesis predicted that decreases in intervals would be smaller when children were younger and greater decreases in intervals when older (Smith, Kenney & Hussain, 1996). Researchers seem to come up with conflicting postulations and inconsistent results about the change trends concerning intervals of segments, syllables, words and phrases, leaving it as an issue unresolved. Most acoustic investigations of children`s speech production have been conducted via cross-sectional designs, which involves studying several groups of children, So far, there are only a few longitudinal studies, This issue needs more longitudinao investigations; moreover, the acoustic measures of the intervals of child speech are hardly available. All former studies focus on word stages excluding the babbling stages especially the canonical babbling stage, but we need to find out when concrete changes of intervals begin to occur and what causes the changes. Therefore, we conducted an acoustic study of interval characteristics of segments and words concerning Canonical Babble (CB) and early speech in an infant aged from 0;9 to 2;4 acquiring Mandarin Chinese, The current research addresses the following two questions: 1, Whether decreases in interval would be greater when children were younger and smaller when they were older or vice versa? 2. Whether the child speech concerning the acoustic features of interval drifts in the direction of the language they are exposed to? The female infant whose L1 was Southern Mandarin living in Changsha was audio- and video-taped at her home for about one hour almost on a weekly basis during her age range from 0;9 to 2;4 under natural observation by us investigators. The recordings were digitized. Parts of the digitized material were labeled. All the repetitions were excluded. The utterances were extracted from 44sessions ranging from 30 minutes to one hour. The utterances were divided into segments as well as syllable-sized units. Age stages are 0;9-1;0,1;1-1;5, 1;6-2;0,2;1-2;4. The subject was a monolingual normal child from parents with a good education. The infant was audio-and video-taped in her home almost every week. The data were digitized, segments and syllables from 44sessions spanning the transition from babble to speech were transcrtbed in narrow IPA and coded for analysis. Babble was coded from age 0;9-1;0 , and words were coded from 1;0 to 2;4, the data has been checked by two professionally trained persons who majored in phonetics. The present investigation is a longitudinal analysis of some temporal characteristics of the child speech during the age periods of 0;9-1;0, 1;1-1;5, 1;6-2;0, 2;1-2;4. The answer to Research Question 1 is that our results are in agreement with neither of the hypotheses. One hypothesis assumed that decreases in intervals would be greater when children were younger and smaller decreases in intervals when older (Theln ,1991); but the other hypothesis predicted that decreases in intervals would be smaller when children were younger and greater decreases in intervals when older (Smith, Kenney & Hussain, 1996). On the whole, there is a tendency of decrease in segmental and syllabic duration with the growing age, but the changes are not drastic and abrupt. For example, /a/ after /k/ in Table 1 has greater decrease during 1;1-1;5, while /a/ after /p/, /t/ and /w/ has greater decrease during 2;1-2;4. /ka/ has greater decrease during 1;1-1;5, while /ta/ and /na/ has greater decrease during 2;1-2;4. Across the age periods, interval change experiences lots of fluctuation all the time. The answer to Research Question 2 is yes. Babbling stage is a period in which the children`s acoustic features of intervals of segments, syllables, words and phrases is shifted in the direction of the language to be learned, babbling and children`s speech emergence is greatly influenced by ambient language. The phonetic changes in terms of duration would go on until as late as 10-12 years of ambient language, the variation, the variation would be less and less until they attain the adult-like competence. Via the analysis of the SPSS 15.0, the decrease of segmental and syllabic intervals across the four age periods to be of no significant is continuous. It reveals that the process of child speech development is gradual and cumulative.

Modules Whose Endomorphism Rings are Unit-Regular

Zhang, Xiaoxiang,Lee, Gangyong Taylor Francis 2016 Communications in Algebra Vol.44 No.2

<P>Unit-regular rings have been extensively studied in the literature. In this article, we introduce the notion of unit endoregular modules which generalizes that of unit-regular rings. A module is called unit endoregular if its endomorphism ring is unit-regular. It is proved that a ring R is a right V-ring if and only if every finitely cogenerated right R-module is unit endoregular. Some characterizations of unit endoregular modules are provided so that several known results on unit-regular rings are generalized. We also provide some properties of unit endoregular modules. For instance, any module which is mutually subisomorphic to a unit endoregular module M is isomorphic to M.</P>

Fuel properties of bio-oil/bio-diesel mixture characterized by TG, FTIR and 1^H NMR

Jiang Xiaoxiang,Zhong Zhaoping,Naoko Ellis 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.1

There has been an increasing interest in alternative fuels made from biomass which is abundant and renewable. Bio-oil and bio-diesel seem to be such promising liquid fuels. Bio-oil produced by fast pyrolysis of biomass is highly viscous, acidic, and has high water content. To overcome these problems as a fuel, a method of emulsifying bio-oil with bio-diesel was performed in the previous paper, and a stable mixture of bio-oil and bio-diesel was successfully prepared. In this paper, several properties of the mixture are discussed by using TG, FTIR and 1^H NMR. The results show us that, compared with crude bio-oil, some properties of bio-oil/bio-diesel mixture such as water content,acid number, viscosity are much improved. The thermal decomposition of the mixture under air/nitrogen is shown using a thermogravimetric analyzer (TGA). Further information about the functional groups is exhibited through Fourier Transform infrared spectrometer (FTIR) and nuclear magnetic spectroscopy (NMR).

Joint Relay-and-Antenna Selection and Power Allocation for AF MIMO Two-way Relay Networks

( Wang Xiaoxiang ),( Zhou Jia ),( Wang Dongyu ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.3

In this paper, we present a joint relay-and-antenna selection and power allocation strategy for multiple-input multi-output (MIMO) amplify-and-forward (AF) two-way relay networks (TWRNs). In our approach, we select the best transmit and receive antennas at the two sources, a best relay and a best transmit and receive antenna at the selected relay based on maximizing the minimum of the end-to-end received signal-to-noise-ratios (SNRs) under a total transmit power constraints. We obtained the closed-form solution for the optimal power allocation firstly. Then with the optimal allocation solution we found, we can reduce the joint relay-and-antenna selection to a simpler problem. Besides, the overall outage probability is investigated and a tight closed-form approximation is derived, which provides a method to evaluate the outage performance easily and fast. Simulation results are presented to verify the analysis.