Synthesis, Characterization and Electrical Properties of Novel Steric Phthalocyanine Polymers

Qiang Liang,Peng Zhao,우재완,박용성,Lihong Niu,Fushi Zhang 한국고분자학회 2010 Macromolecular Research Vol.18 No.2

Two novel steric polymeric phthalocyanines, with copper (CuPPc) and aluminum hybrid zinc (Al/ZnPPc)as the central atoms, were synthesized by the cyclic condensation of tetrahedral tetra-phthalonitriles. The IR and UVVIS spectra of the synthesized polymers indicated a moderate degree of polymerization, somewhere between the monomeric phthalocyanine and planar covalent polymer. Good thermal stability and a high metallic content of CuPPc and Al/ZnPPc were verified by TGA and ICA-AAS methods. The metallic atoms were distributed uniformly and exhibited different binding features with -CN, -O, -N in the polymer, as indicated by EDS and XPS analysis. High electrical conductivity was observed before and after iodine doping compared to the normal polymeric phthalocyanine.

Fuzzy Control Strategy for Course Correction of Omnidirectional Mobile Robot

Niu Zijie,Lu Qiang,Cui Yonjie,Sun Zhijun 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.9

Omnidirectional mobile robots (OMRs) based on the Mecanum wheel, often slide during driving and cause the actual course to deviate from the set heading. To improve the OMR course accuracy, we propose a fuzzyPI control algorithm that modifies the OMR course in real time, by analyzing the omnidirectional movement of the Mecanum wheel and the kinematic model of the OMR. fuzzification, fuzzy reasoning, and defuzzification, the robot’s heading is corrected in real time. Analysis of the yaw error of the robots, with and without the fuzzy PI control algorithm, show that the yaw error has been reduced from the original values of −2.5-0◦ and −10.5-0◦ down to −0.6-0.6◦ and −1-0◦ , when the robot travels a distance of 3.5 m in the longitudinal and transverse directions, respectively. Through experiments, the traditional PI control algorithm and fuzzy PI control algorithm are compared in terms of the robot heading-regulation performance. From the analysis of experimental data, we can see that, when the yaw error of an OMR with the fuzzy PI control algorithm is between 35 and 40◦, the adjustment time is sped up by 1.3 s and 1.2 s and overshoot angle is reduced by 7.7◦ and 4.3◦ , respectively, for longitudinal and transverse movements. Both experimental results show that the fuzzy PI control algorithm has good regulation performance and can achieve good control effects.

Formation of Ethyl Carbamate in Goji wines: Effect of Goji Fruit Composition

Qiang Xia,Meican Niu,Chong-De Wu,Rongqing Zhou 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.3

Ethyl carbamate (EC) is a multisite carcinogen widely occurring in alcoholic beverages. In this investigation, solid-phase extraction combined with gas chromatography mass spectrometry was employed to determine EC contents during the fermentation and storage processes, and the effects of Goji varieties on its formation were also examined. The results indicated that natural and potential EC contents were significantly affected by the varied composition of Goji fruits. The analysis of chemical properties showed differences in hundred-grain weight, water contents, amino acids, and nitrogen-tocarbon ratio for Goji berries. Citrulline was completely degraded although it is routinely considered as a non-preferred nitrogen for yeasts. Due to compositional differences, Goji wines accumulated distinct urea levels that positively correlated with the potential EC contents. Furthermore, the temperature in both the production processes highly influenced EC formation. These results contribute to a more comprehensive understanding of EC formation, and in turn, controlling EC in the Goji wine matrix.

Flexural Behavior and Prediction Model of Basalt Fiber/Polypropylene Fiber-Reinforced Concrete

Qiang Fu,Zhaorui Zhang,Wenrui Xu,Xu Zhao,Lu Zhang,Yan Wang,Ditao Niu 한국콘크리트학회 2022 International Journal of Concrete Structures and M Vol.16 No.5

The flexural behavior of basalt fiber (BF)/polypropylene fiber (PF)-reinforced concrete (BPRC) was investigated. When the content of BF and PF is 0.1%, the addition of fibers increases the compressive strength of concrete. A BF content of 0.1% has the most obvious effect on improving the compressive strength, but a hybrid fiber content of 0.2% exhibits a negative effect on the compressive strength. The addition of BF and PF can increase the flexural strength and the expansion tortuosity of the fracture cracks, thus enhancing the ductility of concrete. The hybrid fibers with content of 0.1% are most beneficial to increase the flexural strength. However, the ductility of concrete and the tortuosity of fracture crack decrease with the matrix strength, and the improvement proportion of fibers on the flexural strength also decreases. When the BF and PF are mixed, compared to the case of single fiber added, there is no significant change in the damage of BF, whereas the damage of PF is more severe. The flexural toughness index FTδ effectively characterizes the change in the flexural toughness of BPRC. The hybrid fiber contents of 0.1% and 0.2% exhibit the most significant improving effect on FT-l/600 and FT-l/150, respectively. Considering the influence of fibers on the compressive strength, flexural strength and flexural toughness of concrete, a hybrid content of 0.1% is the optimal choice of fiber content. A prediction model for flexural strength of BPRC is proposed based on the composite material theory.

A Two-stage CMOS Integrated Highly Efficient Rectifier for Vibration Energy Harvesting Applications

Li, Qiang,Wang, Jing,Niu, Dan,Inoue, Yasuaki The Korean Institute of Electrical Engineers 2014 The Journal of International Council on Electrical Vol.4 No.4

We report, in this paper, a highly efficient CMOS rectifier for low power energy harvesting system. By using two-stage structure and a novel active diode, the rectifier can work at a wide range of input voltage amplitudes of 0.45V up to 1.8V under a standard 0.18um CMOS process. A comparator that consists of common-gate stage and control stage is designed to control the switch of the active diode. The proposed rectifier can achieve a peak voltage conversion efficiency of over 96% and a power efficiency over 90%. Simulated power consumption of the rectifier is 197nW at 450mV, which is about 30% smaller than the best recently published results.

Bit Rate Conditions to Asynchronously Stabilize Event-triggered Multi-dimensional Linear Systems

Yufei Niu,Qiang Ling 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.7

This paper focuses on bit rate conditions to asynchronously stabilize a multi-dimensional linear system based on event triggering. This system transmits control signals through digital communication networks that suffer from processing delay and network delay. So the event-triggering time instants cannot be perfectly known by the controller, which results in the asynchronous state estimation at the sensor and controller sides. To resolve this issue, under the assumption of bounded processing delay and bounded network delay, we propose an event-triggered control strategy to ensure the input-to-state stability for the system. It should be emphasized that this paper does not need to transmit any ACK (Acknowledgment) regarding the receipt of a feedback packet and no clock synchronization is required between the sensor and the controller. Besides the processing delay and the network delay, the coupling among multiple state variables of the multi-dimensional system greatly complicates the event-triggering strategy design and the stability analysis. So we require that the sensor/event-trigger sends the feedback information of each state variable independently and introduce an invertible matrix to simplify the stability analysis. By extracting additional information embedded in the receive time instants of feedback packets, we may obtain a lower bit rate to stabilize the system in the input-to-state sense than periodic sampling methods. The bit rate superiority of our event-triggering strategy is further verified through simulations.

Research on Hybrid Query Expansion Algorithm

Zhixiao Wang,Qiang Niu 보안공학연구지원센터 2012 International Journal of Hybrid Information Techno Vol.5 No.2

Abnormal volumetric thermal expansion in the hourglass fermion materials KHgAs and KHgSb

Chang, Dahu,Niu, Chun-Yao,Huang, Xiaowei,Sun, Qiang,Cho, Jun-Hyung,Jia, Yu American Physical Society 2017 Physical Review B Vol.95 No.10

<P>Using first principles density functional theory calculations combined with quasi-harmonic approximation, we demonstrate that the recently reported nonsymmorphic 'hourglass fermion' materials KHgX (X = As, Sb) belong to a type of negative thermal expansion (NTE) material with an abnormal volumetric thermal expansion. It is revealed that the NTE is caused by the peculiar layered structures of KHgAs and KHgSb, composed of alternately arranged alkali metal and Hg-X atomic layers with residual tensions. Specifically, the coefficients of negative thermal expansion (CNTE) of KHgAs and KHgSb can reach up to -2.7 x 10(-6) K-1 and -4.9 x 10(-6) K-1 along the a axis, respectively, as well as a larger volumetric CNTE of -4.98 x 10(-6) K-1 for KHgSb. The analyses of Gruneisen parameters and vibrational modes show that the NTE of KHgX is driven by the cooperation of membrane and tension effects. It is most likely that the weaker bonds in the Hg-X layer and the smaller mass of alkali metal facilitate the membrane and tension effects, therefore producing a large NTE. Our findings offer insights for understanding the underlying mechanism of NTE behavior in the hourglass fermion materials KHgX.</P>

Gasification reactivity and combustion characteristics of semi‑coke

Meiqin Zha,Wei Xia,Qiang Niu 한국탄소학회 2019 Carbon Letters Vol.29 No.6

Various semi-cokes were obtained from medium–low-temperature pyrolysis of Shenmu long flame coal. The combustion characteristic index and CO2 gasification reactivity of semi-cokes were measured and analyzed using thermogravimetry analysis. The influence of particle size on CO2 gasification reactivities of these semi-cokes was studied. In addition, the Brunauer–Emmett–Teller surface area (SBET), carbon material structure order and carbon crystalline structure were examined by N2 adsorption, Raman spectroscopy and powder X-ray diffraction. All of these properties were used to evaluate the CO2 gasification reactivity of these semi-cokes. The results show that the gasification reactivity of semi-cokes decreases with an increasing crystallinity and structure order. Surface area of the pores is proportional to the reactivity of the semi-coke; the greater the surface area, the faster the gasification reaction rate.

NUMERICAL ANALYSIS AND THEORETICAL PREDICTION OF AXIAL CRUSHING CHARACTERISTICS OF MIXED THIN-WALLED TUBES WITH DUAL-VARIABLE ATTRIBUTE

Xu Feng Xiang,Niu Xiao Qiang,Shao Tian Ru 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.6

Thin-walled structures with varying thickness (single variable attribute) had been proven to be able improve energy absorption characteristics. In order to further study the energy absorption characteristics of thin-walled structures whose material properties changed as the thickness changing, a novel type of mixed thin-walled tube with axially-varying thickness and material were proposed in this paper. The finite element (FE) model was validated under axial quasi-static loading firstly, and seven groups simulation models of thin-walled tubular structure were established. The simulation results showed that the dual-variable attribute tubes can ensure high energy absorption and reduce the initial peak crushing force effectively in the crushing process. Furthermore, the maximum crushing force efficiency of steel-aluminum mixed tube can reach 2.77, while the aluminum mixed tube increased the crushing force efficiency to 1.24. Subsequently, a analytical model for dual-variable attribute tube was established and the theoretical mean crushing force calculation formula can be derived. The simulation and theoretical results were wirelessly close, except that the error of SUT5 was about 11 %. Therefore, the theoretical prediction results were in good agreement with the simulation results, and the theoretical prediction method can provide some reference for the design of double variable tube.