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Signed 2-independence of the Cartesian product of directed cycles
Haichao Wang,김혜경 장전수학회 2019 Proceedings of the Jangjeon mathematical society Vol.22 No.4
A function f : V (D) → {−1; 1} defined on the vertices of a digraph D = (V (D);A(D)) is called a signed 2-independence function if f(N [v]) ≤ 1 for every v in Σ D. The weight of a signed 2-independence function is f(V (D)) = v2V (D) f(v). The signed 2-independence number of a digraph D, denoted by 2 s(D), equals the maximum weight of a signed 2-independence function on D. Let Cm × Cn be the Cartesian product of directed cycles Cm and Cn. In this paper, the exact values of 2 s(Cm × Cn) for 2 ≤ m ≤ 5 and n ≥ 2 are determined.
Equivalent Circuit Model of Novel Solid Rotor Induction Motor with Toroidal Winding
Haichao Feng,Xu Cui,Jikai Si,Caixia Gao,Chun Gan 한국자기학회 2019 Journal of Magnetics Vol.24 No.4
Solid rotor induction motor (SRIM) is widely used in many fields due to its sturdy construction, low maintenance costs, and soft mechanical characteristic. A novel SRIM with toroidal winding (N-TWSRIM) is proposed and its equivalent circuit model (ECM) is established herein. The structure of N-TWSRIM is introduced and its operating principle is analyzed according to the movement of armature magnetic field at different times. The main structural parameters of N-TWSRIM are given, an equivalent circuit model is established to analyze performance of motor, and the results of ECM and two-dimension finite element model (FEM) are compared. Finally, to validate the correctness of operating principle and equivalent circuit model, a prototype of N-TWS-RIM has been built and experimented. It shows that the experimental results are consistent with the finite element and analytical results.
Haichao Cai,Chunguang Xu,Qinxue Pan,Hongjuan Yan 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.10
Ultrasonic guided wave detection technology has numerous advantages compared with body waves. Accurately obtaining the time-of-arrival (TOA) or time-of-flight (TOF) of the ultrasonic guided wave signal is critical for the detection and location of defect because of the frequent use of the low frequency guided wave probe in testing. Thus, guaranteeing the propagation over a long distance and increasing the resolution of defect detection become the key points. This study adds the weighted nonlinear transformation functions to the minimum entropy deconvolution (MED). By adjusting the corresponding parameters, it can enhance a weak signal of small defects and suppress the noise signal. The experimental results indicate that this method can accurately obtain TOA to enhance the resolution of defect detection and can improve the speed of convergence effectively compared with MED.
Output Regulation with Prescribed Performance Control of Switched Strict-feedback Systems
Haichao Zhu 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.3
In this work, we establish a complete procedure for the output regulation problem with prescribed performance for a class of switched strict-feedback systems by employing barrier Lyapunov function and speed function method. Under the framework of output regulation control for general switched nonlinear systems, a switched regulator equation is constructed. Compared to the existing works which require the solvability of output regulation for each subsystem, the designed switched regulator equation based method need not each subsystem has a solution to the problem, which releases the conservatism. Moreover, the state feedback control scheme based on speed function technique and a new state dependent switching rule are constructed to achieve that the error output keeps in a prescribed performance bound in a given finite time and tracks a desired trajectory asymptotically. The effectiveness of the results is demonstrated by a simulation example.
Haichao Feng,Yaohua Guo,Xiaozhuo Xu,Caixia Gao,Liwang Ai 한국자기학회 2023 Journal of Magnetics Vol.28 No.4
In order to meet the demand of high-power density, high-precision positioning and low cost direct drive system in ropeless lifting, precision machining and other fields, the modular secondary structure with permanent magnet synchronous magnetization is adopted in this paper, and the secondary permanent magnet flux-switching linear machine (SPMFSLM) is proposed. Compared with the traditional primary permanent magnet fluxswitching linear machine (PPMFSLM), it reduces the thrust ripple and strengthens the primary structure. According to the topology and operation principle of the machine, starting from the air-gap magnetic field modulation principle and the convex tooth effect, the contribution of the air-gap flux density harmonics of the permanent magnet magnetic field and the armature magnetic field for the two machines to the average thrust is compared and analyzed, reflecting the similarities and differences between the two FSLMs in the thrust generation mechanism. In addition, the no-load characteristics for back-EMF and the thrust characteristics for two machines under equal load are calculated and compared. Finally, the multi-objective optimization of the key structural parameters of the machine is carried out by combining the response surface method (RSM) with the NSGAII algorithm. Then, the 3D simulation of the machine was carried out and cross-validated with the 2D results. Finally, a double-sided SPMFSLM (DS-SPMFSLM) is proposed from the practical point of view. The performance of DS-SPMFSLM is significantly superior to that of single-sided SPMFSLM, which verifies the advantages of the secondary permanent magnet structure scheme.
Domination parameters of strong product of directed paths
Haichao Wang,김혜경 장전수학회 2017 Advanced Studies in Contemporary Mathematics Vol.27 No.3
In a digraph D = (V (D),A(D)), a vertex u dominates a vertex v if u = v or uv ∈ A(D). A set S ⊆ V (D) is a dominating set of D if any vertex of V (D) is dominated by at least one vertex of S. The domination number of D, denoted by γ(D), is the minimum cardinality of a dominating set of D. A two-valued function f : V (D) → {−1, 1} defined on the vertices of D is called a signed dominating function if f(N−[v]) ≥ 1 for every v in D. The weight of a signed dominating function is f(V (D)) = ∑v∈V (D) f(v). The minimum weight of a signed dominating function of D is the signed domination number γs(D) of D. Let Pm ⊠ Pn be the strong product of directed paths Pm and Pn. In this paper, we determine the exact values of γ(Pm ⊠ Pn) and γs(Pm ⊠ Pn) for any m and n, respectively.
Free vibration analysis of uniform and stepped functionally graded circular cylindrical shells
Haichao Li,Fuzhen Pang,Yuan Du,Cong Gao 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.2
A semi analytical method is employed to analyze free vibration characteristics of uniform and stepped functionally graded circular cylindrical shells under complex boundary conditions. The analytical model is established based on multi-segment partitioning strategy and first-order shear deformation theory. The displacement functions are handled by unified Jacobi polynomials and Fourier series. In order to obtain continuous conditions and satisfy complex boundary conditions, the penalty method about spring technique is adopted. The solutions about free vibration behavior of functionally graded circular cylindrical shells were obtained by approach of Rayleigh-Ritz. To confirm the dependability and validity of present approach, numerical verifications and convergence studies are conducted on functionally graded cylindrical shells under various influencing factors such as boundaries, spring parameters <i>et al</i>. The present method apparently has rapid convergence ability and excellent stability, and the results of the paper are closely agreed with those obtained by FEM and published literatures.
Adhesives and Sealants Used in Machinery and Equipment Assembly, Maintain and Repair
Zhai, Haichao,Li, Yinbai,Lin, Xinsong The Society of Adhesion and Interface 2002 접착 및 계면 Vol.3 No.1
In this paper, some idea about the use of Metal and ceramic filled epoxy adhesive, Anaerobic adhesive and RTV silicone in the assembly, maintain and repair of machinery and equipment is given. Many examples which have been successfully used in Chinese industry are introduced: ${\bullet}$ Wear, Abrasion, Corrosion/Erosion Resistance and Metal Rebuilding Worn shafts, Scored Hydraulic Ram, Bearing Housings, Slurry Pumps (Bodies & Impellers), Slide-ways, Heat Exchangers, Cracked Castings and Molds. Leaking Pipes and Tanks. ${\bullet}$ Locking and Retaining Thread, Bearing, Keyways, Bolts, Nuts, Studs, Gears, Collars, Motors. ${\bullet}$ Scaling and Gasketing Flanges, Pipe Joints, Machined surfaces.