Storage-Less and Converter-Less Photovoltaic Energy Harvesting With Maximum Power Point Tracking for Internet of Things

Yiqun Wang,Yongpan Liu,Cong Wang,Zewei Li,Xiao Sheng,Hyung Gyu Lee,Naehyuck Chang,Huazhong Yang IEEE 2016 IEEE transactions on computer-aided design of inte Vol.35 No.2

<P>Energy harvesting from natural environment gives range of benefits for the Internet of things. Scavenging energy from photovoltaic (PV) cells is one of the most practical solutions in terms of power density among existing energy harvesting sources. PV power systems mandate the maximum power point tracking (MPPT) to scavenge the maximum possible solar energy. In general, a switching-mode power converter, an MPPT charger, controls the charging current to the energy storage element (a battery or equivalent), and the energy storage element provides power to the load device. The mismatch between the maximum power point (MPP) current and the load current is managed by the energy storage element. However, such architecture causes significant energy loss (typically over 20%) and a significant weight/volume and a high cost due to the cascaded power converters and the energy storage element. This paper pioneers a converter-less PV power system with the MPPT that directly supplies power to the load without the power converters or the energy storage element. The proposed system uses a nonvolatile microprocessor to enable an extremely fine-grain dynamic power management in a few hundred microseconds. This makes it possible to match the load current with the MPP current. We present detailed modeling, simulation, and optimization of the proposed energy harvesting system including the radio frequency transceiver. Experiments show that the proposed setup achieves an 87.1% of overall system efficiency during a day, 30.6% higher than the conventional MPPT methods in actual measurements, and thus a significantly higher duty cycle under a weak solar irradiance.</P>

Scale effect mechanism research of insect-imitating hexapod robot

Yiqun Liu,Hao Li,Jianfeng Wang,Liang Ding,Tao Liu,Haibo Gao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6

The scale parameter is one of the key factors which influence the structure and locomotion characteristics of the legged robot. The scale effect mechanism of animals in nature was revealed, and the influence of scale parameters on animal was analyzed. This paper establishes a dynamic model of insect-imitating hexapod robot. A high-fidelity simulation platform for hexapod robot was established based on Vortex, and the foot-ground interaction mechanics model was established and applied to the developed simulation platform. Based on the existing six-legged robot prototype, the validity of the relevant model and the fidelity of the simulation platform are verified. The influence of a robot’s mass and characteristic size on its feature locomotion was analyzed. The foot force rises with the increase of the whole robot mass, and the foot force of the unit robot mass decreases with the increase of the whole robot mass, eventually tending to a fixed value. The maximum joint torque rises with the increase of the whole robot mass. The system power rises with the increase of the whole robot mass, but the system power of unit robot mass is basically a constant value. The peak system power decreases with the increase of the distance between the front and the rear leg, and the joint torque rises with the increase of the distance between the front and rear leg. The related research results have guiding significance and reference value for the system design of hexapod robots.

Experimental and Numerical Analysis of the Ribbed Reinforced Concrete Fracture Behavior Based on the Mesoscale FE Model

Zhanliang Wang,Wei Zhang,Yiqun Huang 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.5

This study presented a meso-model for the fracture analysis of the reinforced concrete (RC) structure. A modeling method of RC meso-structure was proposed, and the rebars were allowed to separate from the concrete. The model was built using the cohesive zone model (CZM). The zero-thickness cohesive elements were adopted to characterize the mechanical behavior of potential fracture surfaces and rebar–concrete interfaces. The constitutive model for concrete was developed by considering the damage relation and friction effect, and the corresponding constitutive for the rebar–concrete interface (especially ribbed rebar) was developed by considering the influence of normal separation on the tangential bond–slip relation. To validate the proposed meso-model, a series of ribbed RC beams with an initial notch was designed and tested by four-point bending loading to obtain different fracture patterns. Through comparison, the developed RC meso-model was validated to simulate the RC structure's fracture behavior appropriately. The influence of the rebar–concrete interface constitutive model on the simulation results was investigated. The investigation results indicate that neglecting normal separation would result in an overestimation of the structure's stiffness and bearing capacity (the peak load was overestimated by more than 10%). Finally, an analysis was conducted on the energy consumption during the failure process of the RC beams. It was found that the proportion of energy consumption during tensile failure of the beam decreased from approximately 86% to 89% in the early stage to approximately 43% to 52% in the later stage, indicating a transition in the beam's failure mode from tensile failure to shear failure.

Fluid Mud Dynamics and Its Correlation to Hydrodynamics in Jiaojiang River Estuary, China

Li Li,Wang Jiachen,Zheng Yiqun,Yao Yanming,Guan Weibing 한국해양과학기술원 2023 Ocean science journal Vol.58 No.1

The Jiaojiang Estuary is a macro-tidal estuary with high turbidity and funnel-shaped geomorphology. Estuarine geomorphology and shipping are highly afected by sediments and heavy coastal engineering. Based on observed data and numerical simulation results, we studied the characteristics of the suspended sediments and fuid mud in the estuary. By considering two-way coupling of water–sediment density and the process of fne sediment focculation, a three-dimensional sediment model of the Jiaojiang Estuary was established and efectively calibrated using the measured data on tides, currents, and suspended sediment concentration (SSC). Field data analysis indicated that SSC and sediment transport rate in both the main tidal channel and shoals were positively correlated with the fow velocity in the low-frequency part during both the spring and neap tides. The model results revealed that the net sediment fux is controlled by advection and moves landward upstream of the main tidal channel. Fluid mud is formed near Haimen station, with tides infuencing the spatial and temporal variations in its thickness and speed. Sediment is actively exchanged among fuid mud-water-seabed, with sink and source processes dominating near the bay mouth and the Haimen station, respectively. Sediments weaken the seaward residual currents slightly by changing their viscosity and the von Karman constant, and the stratifcation process is afected by changes in water density. The fndings of this study provide a foundation for the study of material transportation in an estuarine ecosystem.

Static behavior of stud shear connectors with initial damage in steel-UHPC composite bridges

Qi, Jianan,Tang, Yiqun,Cheng, Zhao,Xu, Rui,Wang, Jingquan Techno-Press 2020 Advances in concrete construction Vol.9 No.4

For steel-concrete girders made composite using shear studs, initial damage on studs induced by weld defect, unexpected overloading, fatigue and others might degrade the service performance and even threaten the structural safety. This paper conducted a numerical study to investigate the static behavior of damaged stud shear connectors that were embedded in ultra high performance concrete (UHPC). Parameters included damage degree and damage location. The material nonlinear behavior was characterized by multi-linear stress-strain relationship and damage plasticity model. The results indicated that the shear strength was not sensitive to the damage degree when the damage occurred at 2/3d (d is the stud diameter) from the stud root. An increased stud area would be engaged in resisting shear force as the distance of damage location from stud root increased and the failure section becomes inclined, resulting in a less reduction in the shear strength and shear stiffness. The reduction factor was proposed to consider the degradation of the shear strength of the damaged stud. The reduction factor can be calculated using two approaches: a linear relationship and a square relationship with the damage degree corresponding to the shear strength dominated by the section area and the nominal diameter of the damaged stud. It was found that the proposed method is preferred to predict the shear strength of a stud with initial damage.

Moxibustion for medical personnel with negative emotion and insomnia during COVID-19 pandemic: A randomized, controlled trial

Li Xiying,Li Xiaojuan,Wang Xian,Yin Xuan,Li Shanshan,Wu Junyi,Ren Xiumei,Zhang Wei,Mi Yiqun,Xu Shifen 한국한의학연구원 2023 Integrative Medicine Research Vol.12 No.3

Background: We conducted this randomized controlled trial (RCT) to evaluate the effectiveness and safety of moxibustion at Sanyinjiao (SP6) acupoint for treatment of negative mood and sleep quality in healthcare workers during the 2019 coronavirus disease (COVID-19). Methods: A total of 180 participants were divided in a 1:1 ratio into two groups, the treatment group (for moxibustion) and the control group (for no treatment). The treatment group had a 30-minute moxibustion therapy once a day for two weeks, followed by a two-week follow-up. The Hamilton Anxiety Scale (HAMA) was used to assess the degree of the participants' anxiety, and the Patient Health Questionnaire-9 (PHQ-9) was utilized to examine their depressed condition. The Maslach Burnout Inventory-General Survey (MBI-GS) was used to measure the level of burnout among healthcare workers. To determine the severity of insomnia, the Sleep Dysfunction Rating Scale (SDRS) was utilized. At baseline, week 2, and week 4, all scales were evaluated. Results: Compared to the control group, The treatment group improved more significantly in the HAMA at week 2 (MD = -19.01, 95% CI: -21.89 to -16.14; P<0.001) and at week 4 follow-up visits (MD = -8.96, 95% CI: -11.19 to -6.73; P<0.001). A subgroup study of HAMA scores revealed that position and education had significant impact on treatment effectiveness. During the 2-week intervention period, the treatment group showed more significant improvements in depressive symptoms measured by PHQ-9 (13.00±2.41 vs. 15.60±3.65; P<0.001), work burnout symptoms measured by MBI-GS (MD = -11.88, 95% CI, -15.73 to -8.03; P<0.001), and insomnia symptoms measured by SDRS (MD = -2.45, 95% CI, -4.24 to -0.66; P<0.01). There were no significant adverse effects reported. Conclusion: Moxibustion at SP6 may be an effective treatment to improve anxiety, depression, sleep quality, and quality of life for healthcare workers during COVID-19.

Research on New Nylon-6 Nanocomposites with Flame Retardancy

Jinliang Qiao,Xiaohong Zhang,Yiqun Liu,Weifu Dong,Qingguo Wang,Hua Gui,Jianming Gao,Zhihai Song,Jinmei Lai,Fan Huang 한국고분자학회 2006 한국고분자학회 학술대회 연구논문 초록집 Vol.2006 No.10

Real-World Data of Pyrotinib-Based Therapy in Metastatic HER2-Positive Breast Cancer: Promising Efficacy in Lapatinib-Treated Patients and in Brain Metastasis

Ying Lin,Mingxi Lin,Jian Zhang,Biyun Wang,Zhonghua Tao,Yiqun Du,Sheng Zhang,Jun Cao,Leiping Wang,Xichun Hu 대한암학회 2020 Cancer Research and Treatment Vol.52 No.4

Purpose Pyrotinib is a newly-developed irreversible pan-ErbB receptor tyrosine kinase inhibitor. This study reported the first real-world data of pyrotinib-based therapy in metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC), focusing on efficacy in lapatinib-treated patients and in brain metastasis. Materials and Methods One hundred thirteen patients with metastatic HER2-positive BC treated with pyrotinib-based therapy in Fudan University Shanghai Cancer Center under non-clinical trial settings from September 1, 2018 to March 1, 2019 were included. Results Over half patients have received more than two lines of systematic therapy and exposed to two or more kinds of anti-HER2 agents. Most patients received a combined therapy, commonly of pyrotinib plus capecitabine, or vinorelbine or trastuzumab. Median progression-free survival (PFS) was 6.3 months (range, 5.54 to 7.06 months) and objective response rate (ORR) was 29.5%, with two patients (1.9%) achieving complete response. Lapatinib-naïve patients had significantly longer PFS than lapatinib-treated patients (9.0 months vs. 5.4 months, p=0.001). ORR for lapatinib-treated patients was 23.2%. Thirty-one of 113 patients have brain metastasis. Median PFS was 6.7 months and intracranial ORR was 28%. For patients without concurrent radiotherapy and/or brain surgery, the ORR was very low (6.3%). But for patients receiving concurrent radiotherapy and/or brain surgery, the ORR was 66.7%, and three patients achieved complete response. Most common adverse event was diarrhea. Conclusion Pyrotinib-based therapy demonstrated promising effects in metastatic HER2-positive BC and showed activity in lapatinib-treated patients. For patients with brain metastasis, pyrotinib-based regimen without radiotherapy showed limited efficacy, but when combined with radiotherapy it showed promising intracranial control.