Controlled-Type ZVS Technique without Auxiliary Components for Micro-inverters

Zhang, Qian,Zhang, Dehua,Hu, Haibing,Shen, John,Batarseh, Issa The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6

This paper proposes a Boundary Current Mode (BCM) control scheme to realize soft switching on a conventional single phase full bridge DC/AC inverter. This technique with the advantages of no auxiliary components, low cost, high efficiency, and simple in control, is attractive for micro-inverter applications. The operation principle and characteristic waveforms of the proposed soft switching technique are analyzed in theory. A digital controller is provided based on that theory. To balance the requirements of efficiency, switching frequency, and inductor size, the design considerations are discussed in detail to guide in BCM inverter construction. A 150W prototype is built under these guidelines to implement the BCM control scheme. Simulation and experiment results demonstrate the feasibilities of the proposed soft switching technique.

Guaranteeing Deadlines for Inter-Data Center Transfers

Zhang, Hong,Chen, Kai,Bai, Wei,Han, Dongsu,Tian, Chen,Wang, Hao,Guan, Haibing,Zhang, Ming Institute of Electrical and Electronics Engineers, 2017 IEEE/ACM transactions on networking Vol.25 No.1

<P>Inter-data center wide area networks (inter-DC WANs) carry a significant amount of data transfers that require to be completed within certain time periods, or deadlines. However, very little work has been done to guarantee such deadlines. The crux is that the current inter-DC WAN lacks an interface for users to specify their transfer deadlines and a mechanism for provider to ensure the completion while maintaining high WAN utilization. In this paper, we address the problem by introducing a deadline-based network abstraction (DNA) for inter-DC WANs. DNA allows users to explicitly specify the amount of data to be delivered and the deadline by which it has to be completed. The malleability of DNA provides flexibility in resource allocation. Based on this, we develop a system called Amoeba that implements DNA. Our simulations and test bed experiments show that Amoeba, by harnessing DNA's malleability, accommodates 15% more user requests with deadlines, while achieving 60% higher WAN utilization than prior solutions.</P>

Controlled-Type ZVS Technique without Auxiliary Components for Micro-inverters

Qian Zhang,Dehua Zhang,Haibing Hu,John Shen,Issa Batarseh 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6

This paper proposes a Boundary Current Mode (BCM) control scheme to realize soft switching on a conventional single phase full bridge DC/AC inverter. This technique with the advantages of no auxiliary components, low cost, high efficiency, and simple in control, is attractive for micro-inverter applications. The operation principle and characteristic waveforms of the proposed soft switching technique are analyzed in theory. A digital controller is provided based on that theory. To balance the requirements of efficiency, switching frequency, and inductor size, the design considerations are discussed in detail to guide in BCM inverter construction. A 150W prototype is built under these guidelines to implement the BCM control scheme. Simulation and experiment results demonstrate the feasibilities of the proposed soft switching technique.

High-efficiency technique for five-axis side milling of niemann worm wheels

Haibing Wu,Zheng Zhang,Quanping Sun 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6

Five-axis side milling technique for Niemann worm wheel teeth flank using a tapered flat-end mill is presented. Equations describing the worm wheel tooth flank were derived based on differential geometry and the working principle of gears. The tooth flank was modified by offsetting its point cloud computed using these equations along the normal direction. The maximum normal curvature of the worm wheel tooth flank was computed, and its minimum radius of curvature was obtained. The cutter path step length and spacing between cutter travels were computed to generate a uniform path for five-axis machining. Software simulations of the cutter path were performed for validation and for analysing errors in the worm wheel tooth flank machining; this technique was also verified by milling worm wheels. The results demonstrated that the technique not only improved machining efficiency by 5 times compared with point milling but also guaranteed precision machining of the tooth flank for five-axis machining of cylindrical worm drives.

Selective molecular recognition on calixarene-functionalized 3D surfaces

Zhang, Fan,Sun, Yue,Tian, Demei,Shin, Weon Sup,Kim, Jong Seung,Li, Haibing The Royal Society of Chemistry 2016 Chemical communications Vol.52 No.86

<P>Host-guest recognition plays an important role in biological analysis and biosensing. Accordingly, great efforts have been devoted to the development of sensors using versatile 3D surface materials. These functionalized nanomaterials possess the advantages of high selectivity and visual signals, enabling the selective detection of ions, amino acids, proteins, and other biological molecules. Therefore, in this feature article, we present some significant and representative examples of molecular recognition on calixarene functionalized 3D surface nanomaterials. By virtue of host-guest interactions, the functional interfaces displaying high selectivity and featuring a reversible switch response towards the environmental stimuli with various signal output (electrochemical and optical signals) are herein introduced. Furthermore, various 3D surface materials with unique signal amplification in molecular recognition are presented, including quantum dots (QDs), metal nanoparticles (NPs), nanotubes, and mesoporous silica. These excellent properties enable calixarene-functionalized 3D materials to become an outstanding platform for molecular recognition, offering convenient approaches for sensing and separation.</P>

Influence of different electrical boundary conditions on the elasticity solutions of piezoelectric plane beam

Zhang Lang,Li Xuewu,Wang Yuping,Wang Qiang,Shi Haibing 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.12

Influence of different electrical boundary conditions (BCs) on the elasticity solutions of piezoelectric plane beam (PPB) is investigated using analytical technique. The first case is considering electrical displacement of the two longitudinal sides of PPB. The second case is electrical potential. Firstly, the unified equations to obtain the elasticity solutions of PPB corresponding to these two cases are given briefly. Secondly, two examples are given to verify the correctness of the theoretical formulations presented in this paper. Finally, the responses of PPB acted by the same mechanical loads but with different electrical BCs are compared.

Accuracy analysis of generalized discrete Fourier transform‑based harmonics extraction in presence of background harmonics

Shuo Zhang,Yuzheng Xia,Tao Yang,Xiang Li,Daorong Lu,Haibing Hu 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.1

The generalized discrete Fourier transform (GDFT) realizes the rapid extraction of specific order harmonics, and shortens the extraction time to 1/3 of a fundamental cycle (6.7 ms at 50 Hz grid) for 6r ± 1 order harmonics. However, the GDFT becomes less accurate when the system presents background harmonics other than specific-order harmonics in the inputs. Therefore, this paper analyzes the influence introduced by these background harmonics on the GDFT. First, the frequency feature of the GDFT is derived by a geometric method based on the z-domain unit circle. Then, the extraction of the 6r ± 1 order harmonics is taken as an example to show the extraction accuracy of the GDFT. The Accuracy of Harmonic Extraction (AHE) index, is also given to evaluate the accuracy of the extraction. Simulation and experimental results confirmed the correctness of the theoretical analysis by showing that the GDFT has the same accuracy as the RDFT when only 6r ± 1 order harmonics are involved. However, if there are other background harmonics in the inputs, the extraction accuracy is affected greatly. Therefore, when the background harmonics cannot be ignored, it is necessary to analyze the AHE of the GDFT. When AHE > 95%, the GDFT has good accuracy and is applicable to real applications.

Study on the Mechanical Properties and Microstructure of Geogrid Under Different Materials and Temperatures

Junli Gao,Haibing Zhang,Xuelei Xie,Yapo Zhang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.6

In response to the environmental problems caused by the difficulty of direct degradation of the raw materials usedin traditional geogrids and the impact of different temperatures on the mechanical properties of geogrids in practicalengineering applications, based on 3D printing technology, polylactic acid (PLA), carbon fiber reinforced polylactic acid(PLA/CF), and thermoplastic polyurethane (TPU) geogrids were fabricated. The 3D printed geogrids and the fiberglassgeogrids used in the actual project were tested in indoor tensile tests under different temperature conditions. The mechanicalproperties of the geogrids of the four kinds of materials and six kinds of temperature were analyzed. The microstructure of thegeogrids after tensile tests was investigated based on scanning electron microscopy technology to further analyze the effectsof different materials and temperatures on the mechanical properties of the geogrids. The results showed that the tensilestrength of PLA/CF geogrids and PLA geogrids decreased with increasing temperature. The tensile strength of fiberglassgeogrids increased with rising temperatures. The tensile strength of PLA/CF geogrids was significantly better than PLAgeogrids. Due to the addition of carbon fiber in PLA, PLA/CF can bear more tensile force at high temperatures. With theincrease of temperature, the elongation at break of PLA/CF geogrids and fiberglass geogrids increased, but the elongation atbreak of PLA geogrids decreased. The elongation at break of PLA/CF geogrids was significantly lower than that of PLAgeogrids. TPU geogrids had high tensile capacity in a high-temperature environment, and they also had high elasticity andmore significant elongation at break, which was not suitable to be used as geogrid material.

Synthesis of (co-)polyethylene with broad molecular weight distribution by the heterogenous Ziegler–Natta catalysts via one-pot strategy

Zhi Liu,Xinli Zhang,Haibing Huang,Jianjun Yi,Wei Liu,Weijiao Liu,Hongpeng Zhen,Kejing Gao,Mingge Zhang,Wantai Yang,Qigu Huang 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.6

A new method was presented for preparing (co-)polyethylene with broad molecular weight distribution (MWD) and high molecular weight employed by the novel heterogeneous Ziegler–Natta catalysts via one-pot strategy. The preparation of these catalysts involved the introduction of alkoxy silane compounds as electron donors. The influences of the electron donors structure, as well as polymerization conditions such as temperature, molar ratio of Al/Ti, ethylene pressure and the concentration of 1-hexene in feed on the polymerization performance for ethylene (co-)polymerization, were investigated. The morphology of the catalyst particles was characterized by SEM and Ti content of these catalysts was characterized by ICP. The GPC results showed that the obtained homopolyethylene and ethylene/1-hexene copolymer had the widest molecular weight distribution up to ca 50 when diethoxy-isopropoxy-(t–butoxy)-silane (ED3) was used as internal electron donor. The 13C NMR and FT-IR analysis indicated that these catalysts efficiently catalyzed the copolymerization of ethylene with 1-hexene.

Simultaneous Impact of Multiple Droplets on Liquid Film

Gangtao Liang,Tianyu Zhang,Haibing Yu,Hongliang Chen,Shengqiang Shen 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.65 No.-

Multiple droplets impinging on a thin liquid film simultaneously is numerically studied using a three-dimensional model with an implement of a random disturbance subjected to Gaussian distribution. This model is very effective to predict droplet splashing under relatively high impingement momentum. Interface evolutions and field distributions are addressed after droplets impact. Besides, a geometric model is built up to demarcate the impact region into two semicircular regions and a series of rectangular regions during simultaneous impact, further to discuss the variations of area and residual film thickness in each region as well as the total area and average film thickness.