Initial Structure Design Research Articles

Design and Analysis of Surface-Mounted Permanent-Magnet Field-Modulation Machine for Achieving High Power Factor

Along with the establishment of general air-gap field modulation theory, a new type of field-modulation machine has attracted increasing attention. However, the low power factor always plagued its popularization. This paper is to focus on the simplest structure surface-mounted permanent-magnet field-modulation (SMPMFM) machine, aiming at exploring the implementation of high power-factor design. The key is that the power factor calculation formula is derived parametrically, hence the originally vague causal relationship between the structural parameters and power factor become clear, guided by which the initial structure design for high power factor achievement is determined, meanwhile the power factor adjustment evaluation and the electromagnetic performance comparison with the help of finite element analysis (FEA) are conducted to verify the validity of the proposed power factor calculation formula. Finally, a feasible high-power-factor SMPMFM prototype is fabricated and the experimental testing is performed, which has a good agreement with the formular calculation and FEA results. Hence, the validity of the proposed analysis for achieving high power-factor design of field-modulation machines is verified.

Initial Structure Design and Optimization of an Automotive Remote Head-Up Display

Aiming at the problems of difficult construction and occlusion of the initial structure of an automotive augmented reality head-up display (AR-HUD), a method to quickly build the initial structure of an automotive AR-HUD is proposed. Firstly, the position of the mirrors in the initial structure is calculated based on the Rodrigues rotation formula. Secondly, the position of the mirrors is restricted by constraints during optimization to prevent the problem of structural occlusion. Finally, a virtual image display system with a visual distance of 7.5 m and a field of view angle of 10° × 5° is designed. The image quality analysis of the optimized system shows that the light spots in each field of view are all within Airy spots. At the spatial cutoff frequency of the virtual image plane of the optical system, the modulation transfer function (MTF) value of the full field of view is basically greater than 0.5, and the distortion is less than 1%. Finally, using the image for simulation, the results of the simulation image are satisfying, which proves the validity and feasibility of the structural design. It provides a useful reference for the structural design of the remote head-up display system.

Initial Structure Design for Refractive Optical System Based on Deep Learning

Initial Structure Design for Refractive Optical System Based on Deep Learning

High performance telescope system design for the TianQin project

China is planning to construct a new space-borne gravitational-wave (GW) observatory, the TianQin project, in which the spaceborne telescope is an important component in laser interferometry. The telescope is aimed to transmit laser beams between the spacecrafts for the measurement of the displacements between proof-masses in long arms. The telescope should have ultra-small wavefront deviation to minimize noise caused by pointing error, ultra-stable structure to minimize optical path noise caused by temperature jitter, ultra-high stray light suppression ability to eliminate background noise. In this paper, we realize a telescope system design with ultra-stable structure as well as ultra-low wavefront distortion for the space-based GW detection mission. The design requirements demand extreme control of high image quality and extraordinary stray light suppression ability. Based on the primary aberration theory, the initial structure design of the mentioned four-mirror optical system is explored. After optimization, the maximum RMS wavefront error is less than λ/300 over the full field of view, which meets the noise budget on the telescope design. The stray light noise caused by the back reflection of the telescope is also analyzed. The noise at the position of optical bench is less than 10−10 of the transmitted power, satisfying the requirements of space GW detection. We believe that our design can be a good candidate for TianQin project, and can also be a good guide for the space telescope design in any other similar science project.

Rigid Procedure to Calculate the Melting Point of Metal Using the Solid-Liquid Phase (Coexistence) Method

Melting point, particularly metal, is one of the important data for many applications. For developing new materials, adequate theories for melting point are very crucial. The determination of melting point using the popular phase-change curve method is very easy but usually overestimate. In current work, we determine the melting point of a pure metal (iron) using the method of solid-liquid phase coexistence. For this goal, molecular dynamics simulation was applied to obtain data of trajectories of atoms. Simulation (LAMMPS) and data analysis (OVITO) procedures are strictly applied to obtain the accurate melting point of iron based on the obtained trajectories data. For initial structure design of simulation, we used the ATOMSK program. The melting point of iron obtained using the phase change curve (PCC) method is about 2750 K < TPCC < 3250 K and using the coexistence phase (CP) method is TCP = 2325 K. A more accurate calculation needs to include defects factor in the simulated material and calculation. In this research we use the Morse potential to represent all of the atomic interaction among atoms of Fe material.

Design and synthesis of novel quinazolinone-pyrazole derivatives as potential α-glucosidase inhibitors: Structure-activity relationship, molecular modeling and kinetic study

In this study, a new series of quinazolinone-pyrazole hybrids were designed, synthesized and screened for their α-glucosidase inhibitory activity. The results of the in vitro screening indicated that all the molecular hybrids exhibited more inhibitory activity (IC50 values ranging from 60.5 ± 0.3 µM-186.6 ± 20 μM) in comparison to standard acarbose (IC50 = 750.0 ± 10.0 µM). Limited structure–activity relationship suggested that the variation in the inhibitory activities of the compounds affected by different substitutions on phenyl rings of diphenyl pyrazole moiety. The enzyme kinetic studies of the most potent compound 9i revealed that it inhibited α-glucosidase in a competitive mode with a Ki of 56 μM. Molecular docking study was performed to predict the putative binding interaction. As expected, all pharmacophoric moieties used in the initial structure design playing a pivotal role in the interaction with the binding site of the enzyme. In addition, by performing molecular dynamic investigation and MM-GBSA calculation, we investigated the difference in structural perturbation and dynamic behavior that is observed over α-glycosidase in complex with the most active compound and acarbose relative to unbound α-glycosidase enzyme.

Design and topology optimization of air conditioning suspension bracket for metro.

During the operation of subway vehicles, the vibration of air conditioning units is mainly transmitted to the vehicle body through the suspension support, which seriously affects the stability and comfort of the vehicle during operation. Therefore, the design and optimization of the suspension support of air conditioning units has become a hot topic in the research of the dynamic characteristics of subway vehicles. In this paper, the rigid and flexible coupling dynamic model of metro is firstly calculated to simulate the stress of the suspension point of air conditioning of the vehicle body when the vehicle is running. The initial structure design of the suspension support is carried out, and the stress of the air conditioning suspension point is taken as the load input to analyze the stiffness and strength of the initial structure of the suspension support. Then, the fatigue life is taken as the topology constraint, and the variable density method (SIMP) is used to optimize the topology of the suspension bracket. Finally, the optimized suspension support is validated. The results show that after topological optimization, the maximum displacement and maximum stress of the suspension support under vertical, horizontal, and vertical loads are reduced by 80%, 93%, and 99%, respectively, compared with the original structure model, and the maximum stress under vertical loads is reduced by 50%.

Optical design of Schwarzschild imaging spectrometer with freeform surfaces

The classical Schwarzschild imaging spectrometer consists of a plane grating and three spherical mirrors. It suffers from a slow optical speed and a small field of view (FOV). Furthermore, astigmatism aberration is present in the conventional configuration due to the dispersion of the plane grating. In this study, a group design method was developed to design a Schwarzschild imaging spectrometer with freeform surfaces. The group design method corrects the astigmatism aberrations in the collimating system and focusing system separately and gives a higher-performing initial structure. To achieve fast optical speed and a larger FOV, freeform surfaces are used to correct the large off-axis aberration. Based on this method, a Schwarzschild imaging spectrometer with a fast optical speed (F/2) and large FOV (32 mm slit) using freeform surfaces is proposed. The initial structure design, optimization procedure, and tolerance analysis are described in detail. The design results indicate that good optical performance and manufacturability of the system are obtained.

50X five-group inner-focus zoom lens design with focus tunable lens using Gaussian brackets and lens modules.

This study presents a 50X five-group zoom lens design with two moving groups and one focus tunable lens (FTL) by applying Gaussian brackets and lens modules. After qualitative analysis of the paraxial properties, the initial structure is obtained by solving the power equations consisting of five groups by numerical analysis method. The optimized nearly 60X lens has a focal length of 5.1-300mm and f-number of 1.8-5.0 in wide and tele positions, with a total length of 160mm. The lens achieves a maximum FOV of 63° at short focal length. The tolerance analysis indicates that the design is suitable for mass production. The method eases the difficulty in initial structure design of the zoom lens with high zoom ratio, improves its optical design efficiency, and can be applied to the fields such as customs security cameras, military detecting devices, machine vision and industrial inspection, etc.

Aberration correction for ellipsoidal window optical system based on Zernike mode coefficient optimization

The traditional window of high-speed aircraft is hemispherical, and the aberration produced by such a window is constant. However, the hemispherical window is difficult to meet the requirements of a high speed flight of aircraft. Aspheric windows are usually used to replace hemispherical windows to increase the aerodynamic performance. However, the aspheric window will introduce dynamic aberrations that fluctuate with the change of scanning field-of-view (FOV), which becomes the key issue of the development of optoelectronic imaging systems for high-speed aircraft. For the ellipsoidal window optical system with scanning FOV of ±60°, an aberration correction method in large FOV combined with the static correction and non-wavefront-sensor adaptive optical correction is studied. In the initial optical structure design, the types of system aberration are reduced and the fifth-order Zernike aberration is eliminated during initial aberration correction, thus, the number of the subsequent adaptive optimization control variables is reduced. According to the characteristics of the deformable mirror, the driving voltage of the driver is generally taken as a variable of the genetic algorithm. However, when the deformable mirror used has many units, too many variables will directly lead the optimization speed of the algorithm to greatly decrease. So, according to the aberration characteristics of the ellipsoidal optical window, using the conversion matrix between the Zernike polynomial coefficients and the voltages of the deformable mirror driver, the optimization variable is reduced from 140 driver voltages to 2−9 Zernike stripe polynomial coefficients in number. Finally, the genetic algorithm based on Zernike model is used to control the shape of the deformable mirror and correct the residual aberration. Taking 2−9 Zernike mode coefficients, 2−16 Zernike mode coefficients and 140 driver voltages as the variables of genetic algorithm respectively, the optimization generations of genetic algorithm under different variables are obtained. The simulation results show that the optimization speed of each typical scanning field of view is increased more than 95% by changing the variable from 140 driver voltages to 2−9 Zernike mode coefficients, and the imaging quality is close to the diffraction limit. This optimization method can not only correct the aberrations caused by the special-shaped optical window, but also compensate for the error caused by processing and aligning the optical system.

A Stochastic Model of Cascading Failure Dynamics in Communication Networks

In this brief, we propose a stochastic model based on state transition theory to investigate the dynamics of cascading failures in communication networks. We describe the failure events of the nodes in the network as node state transitions. Taking a probabilistic perspective, we focus on two uncertain conditions in the failure propagation process: which node in the network will fail next and how long it will last before the next node state transition takes place. The stochastic model gives each overloaded element a probability of failing, and the failure rate is relevant to the degree of overloading. Moreover, the time dimension is considered in the stochastic process, by removing a node after a time delay when its traffic load exceeds its capacity. We employ this proposed model to study the dynamics of cascading failure evolution in a Barabasi–Albert scale-free network and an Internet AS-level network. Simulation results reveal the effects of the initial failure pattern, community structure and network design parameters on the dynamic propagation of cascading failures.

Crack Analysis of Multi-plate Intersection WeldedStructurein Port MachineryUsing Finite Element Stress Calculation andAcoustic Emission Testing

Crack is the main inducement of failure accidents in welded structures of port machinery. Taking actual engineering problems occurred in a coal wharf as a case where a stacker reclaimer altered its local structure (bucket wheel changed to be chute) and then cracks appeared on the Slew deck with pylon after half a year. Using the finite element simulation combined with acoustic emission testing, the stress concentration and crack active status of the multi-plate intersection welded structure were inspected, which aimed at monitoring the development trend of the cracks and finding out reasons. Finite element stress calculation method adopts Solidworks, ANSYS and Hypermesh software co-simulation to explore the effects of mesh type and density on the stress calculation results of the Slew deck with pylon structure, and to analyze the stress distribution of the multi-plate intersection shell structures. According to the analysis results, this paper infers the reasons for crack propagation. Combined with the regular monitoring of acoustic emission testing technology on the active state of cracks and the intensity of expansion, the influences on the apparatus are deduced by the crack states of the bucket wheel reclaimer operations under different working conditions. And then put forward measures for a whole reasonable structure of the rectification and crack repair plans. The results of the research show that: 1) The maximum stress value following the change decreases slightly，which indicates that structure change is not the direct reason for cracking, instead, it is the initial structure design problems; 2) The imbalance torque produced in the boom hinge point after the change is the direct reason for causing cracks; 3) The proposed repairing scheme significantly reduces the stress at the cracks, and improves the fatigue strength. Finite element simulation combined with acoustic emission testing method provides effective means for analysis and prediction of cracks occurred in multi-plate intersection welded structure of port machinery.

Initial structure design of coaxial six-ten mirror central-obscured extreme ultraviolet lithographic objective.

The high numerical aperture projection objective for industrial extreme ultraviolet lithography (EUVL) usually includes several mirrors with central obscuration in the light path. We apply the grouping design method on the spherical initial structure of central-obscured six-ten mirrors EUVL objective. A new condition called obscuration condition is introduced for the parameter calculation of the central-obscured mirror groups. The non-obscured mirror groups in the projection objective were calculated by the non-obstruction condition and conjugation condition, which is based on the object-image relationship and the pupil-stop relationship. By analyzing the expression of obscuration condition and the non-obstruction condition, the combined available ranges of parameters can be obtained. The available mirror group is picked up from that available range and connected to form a whole initial spherical structure. The design process of a six-mirror objective with central obscuration and initial structures with eight-ten mirrors designed by the same process is shown in this article.

소형궤도차량(PRT) 차체의 설계사양 도출 및 구조강도 평가 연구

PRT(Personal Rapid Transit) system is a new transportation system which will meet increasing demands of traffic in Korea. It is also an environment-friendly transportation and automatically operated. For these reasons, researches on the PRT system are actively undergoing, but the PRT vehicles have different forms of subway, bus, etc. There are no design standards to evaluate structural integrity, yet. In this paper, Structural design specifications are derived, which are based on the performance test standard for EMU and the ASCE-APM standards. We also perform the static and fatigue analyses by FE simulation and suggest strategies to improve an initial structure design. In addition, we derived the design specifications for energy-absorbing structures to meet the conditions of the collision scenarios predefined from a view point of operation safety.

Research on Simulation Optimization and Experiment of Dynamical Vibration Absorption Boring Bar with Damping

The build-in dynamical vibration absorption system with damping is applied to increase the dynamic stiffness of a boring bar. According to construction and vibration features, multi flexible body dynamical model of the vibration absorption system is built up by using the software of ADAMS and ANSYS. Also the vibration characteristic of an actual boring bar is analyzed by using SA-78 2ch FFT analyzer. Through the analysis of simulation results and experimental data the accuracy of the model is validated. On this basis the influence of the radial stiffness coefficient of rubber brushes, the damping coefficient of damping fluid and the mass of heavy turning body on the vibration system is discussed by using the vibration analyses module of ADAMS. The simulation results verify the feasibility of the initial structure design; establish the design key points in the actual design. The multi flexible body dynamical model of the vibration absorption system has been simulated, optimized and analyzed. And optimized parameters are obtained finally. With these optimized parameters, actual dynamical vibration absorption boring bar with damping can be designed, and the dynamic stability of the bar is enhanced thereby.

A simplified method for assessing the ductile behaviour of stud connectors in composite beams with high strength concrete slab

Local connection shear failure in the absence of adequate connection ductility can reduce steel and concrete composite element bending resistance. For these elements, Eurocode 4 contains design rules and criteria for checking that implicitly prevent early connection rupture, by limiting the value of the parameters influencing maximum slip capacity. Such indirect ductility checks can, however, only be applied within the constraints of their formulation hypotheses, such as material strength as specified in the document for instance. The use of high strength concrete substantially changes the ratio between maximum slip requirement and connection deformation capacity and demands direct connection ductility checking. This paper identifies the magnitudes affecting maximum slip requirement and suggests a simplified assessment method. The method, having general application, enables assessing connection efficiency to bending collapse of the composite beams and is particularly useful at the initial structure design stage as no demanding sophisticated analysis is required.