Initial Structure Parameters Research Articles

Optimization and thermal characterization of a new liquid-cooled plate with branching channels of fractal geometry

In order to improve the heat transfer effect of the liquid-cooled plate with the traditional straight channel, 24 new liquid-cooled structures were obtained based on the fractal concept by adding 6 geometrically structured branch channels to the traditional straight channel and adding different forms of secondary channels between the branch channels and between the branch channels and the main channel. On the basis of establishing a numerical simulation model and verifying the accuracy of the model, the thermal characteristics of 24 liquid-cooled structures were analysed by computational fluid dynamics (CFD) simulation, and the initial relative optimal liquid-cooled channel structure was obtained by taking the comprehensive thermal performance as the evaluation index. Then, the initial relative optimal channel structure parameters were optimised in steps using NSGA-II and grey relational analysis algorithms. In order to further improve the heat transfer effect of the liquid-cooled plate, the relative optimal model after stepwise optimization was arced. The final results showed a decrease in the average temperature by 0.57 °C (1.6 %), an increase in the heat transfer coefficient by 356 W m−2 k−1 (21.3 %), and a decrease in the pressure drop by 34.55 Pa (50.2 %), as compared with the initial model. This study will provide some reference for the optimisation of the internal structural features of the channel and the improvement of the thermal performance of the liquid-cooled plate.

Initial structure parameters determination and aberration optimization method for ultra-wide angle optical system with large aperture

Initial structure parameters determination and aberration optimization method for ultra-wide angle optical system with large aperture

Optimizations of structure stiffnesses and sensitivities of Y-type six-axis force/torque sensor

PurposeThe six-axis force/torque sensor based on a Y-type structure has the advantages of simple structure, small space volume, low cost and wide application prospects. To meet the overall structural stiffness requirements and sensor performance requirements in robot engineering applications, this paper aims to propose a Y-type six-axis force/torque sensor.Design/methodology/approachThe performance indicators such as each component sensitivities and stiffnesses of the sensor were selected as optimization objectives. The multiobjective optimization equations were established. A multiple quadratic response surface in ANSYS Workbench was modeled by using the central composite design experimental method. The optimal manufacturing structural parameters were obtained by using multiobjective genetic algorithm.FindingsThe sensor was optimized and the simulation results show that the overload resistance of the sensor is 200%F.S., and the axial stiffness, radial stiffness, bending stiffness and torsional stiffness are 14.981 kN/mm, 16.855 kN/mm, 2.0939 kN m/rad and 6.4432 kN m/rad, respectively, which meet the design requirements, and the sensitivities of each component of the optimized sensor have been well increased to be 2.969, 2.762, 4.010, 2.762, 2.653 and 2.760 times as those of the sensor with initial structural parameters. The sensor prototype with optimized parameters was produced. According to the calibration experiment of the sensor, the maximum Class I and II errors and measurement uncertainty of each force/torque component of the sensor are 1.835%F.S., 1.018%F.S. and 1.606%F.S., respectively. All of them are below the required 2%F.S.Originality/valueHence, the conclusion can be drawn that the sensor has excellent comprehensive performance and meets the expected practical engineering requirements.

Performance Analysis of a Novel Axial Radial Flux Segmental Rotor Switched Reluctance Motor

Based on the characteristics of axial flux switched reluctance motor (SRM) and radial flux SRM, this paper proposes a new type of axial radial flux segmental rotor switched reluctance motor (ARFSRSRM). The motor has the left and right dual axial stator structures, which forms a kind of axial flux path with the segmental rotor in the middle, and a radial stator structure, which shares a kind of radial flux path with the segmental rotor on the outside of the motor. Compared with the conventional SRM, this motor combines the advantages of high output torque and torque density due to the inclusion of two kinds of flux paths, making it suitable for high-efficiency and high-torque fields such as electric vehicles. In this paper, the topology and operating principle of the new motor are first introduced. Then the initial structural parameters are derived, and the multi-objective optimization of the proposed motor is carried out using Taguchi’s algorithm. The static and dynamic performance of the motor is comprehensively analyzed using the 3-D finite element method. Finally, the experimental results obtained through the trial production of a prototype machine verify the good performance of the new motor.

Design of Parabolic Off-Axis Reflector Optical System for Large Aperture Single Star Simulators

This study proposes a parabolic off-axis reflective optical system design method to reduce the wave aberration of the optical system of a large aperture single star simulator and improve the optical system’s imaging quality. Firstly, we determined the design indexes of the optical system of the large aperture single star simulator by analyzing the technical indexes of the star sensitizer and the development status of the single star simulator; secondly, the initial structural parameters of the optical system were calculated based on the theory of primary aberration; then, we carried out the design optimization of the optical system, the image quality evaluation, and the tolerance analysis using Zemax software; finally, the study tested the wave aberration of the optical system by using the four-dimensional interferometer and the standard mirror together. The simulation results of the optical system are as follows: in the entire field of view, the aberration of the optical system is far less than 0.002%, the modulation transfer function (MTF) reaches the diffraction limit, and the maximum wave aberration is 0.0324 λ. The experimental results are as follows: the maximum wave aberration of the optical system is 0.0337 λ, which is less than 1/25 λ, and it meets the requirements of the index. The simulation and experimental results show that the optical system of the large aperture single star simulator designed by this method has good imaging quality and a simple system structure.

Control of nano-cavitation in semi-crystalline polymer nanocomposites during uniaxial tension: In situ synchrotron X-ray study

The cavitation behavior of polypropylene-silica (PP-silica) and high density polyethylene-silica (HDPE-silica) composites with varying silica content during uniaxial tension was investigated via in situ X-ray techniques. The introduction of silica was found to significantly influence the mechanical properties of the materials. Small-angle X-ray scattering (SAXS) was employed to determine the cavitation onset strain and to observe the evolution of cavity structures. Through model fitting, the size evolution of nanoscale cavities at the onset of cavitation was quantitatively characterized. Scanning electron microscopy (SEM) was utilized to examine the morphology before and after stretching, revealing that cavity structures primarily resulted from internal defects in the polymer matrix and interfacial debonding between silica and the polymer. The long axis of the nanoscale cavities at the onset of cavitation was perpendicular to the tensile direction, and further deformation led to the coalescence into micron-sized cavities with the long axis parallel to the tensile direction. Wide-angle X-ray scattering (WAXS) was used to characterize the microscale deformation process of crystals, showing that during stretching, the lamellae reoriented with the angle between their normal direction and the tensile direction gradually decreasing. Several sets of transition strains representing the plastic deformation were used to compare the microscale and macroscale deformation, elucidating the sequence and differentiation between crystal plastic deformation, cavitation, and yield in the two polymer materials. Intriguingly, both PP-silica and HDPE-silica composites exhibited optimal silica additions and initial structural parameters for regulating cavitation behavior. These findings offer significant guidance for the control of internal structures in porous separators in industrial production.

Temperature-induced DNA density transition in phage λ capsid revealed with contrast-matching SANS.

Structural details of a genome packaged in a viral capsid are essential for understanding how the structural arrangement of a viral genome in a capsid controls its release dynamics during infection, which critically affects viral replication. We previously found a temperature-induced, solid-like to fluid-like mechanical transition of packaged λ-genome that leads to rapid DNA ejection. However, an understanding of the structural origin of this transition was lacking. Here, we use small-angle neutron scattering (SANS) to reveal the scattering form factor of dsDNA packaged in phage λ capsid by contrast matching the scattering signal from the viral capsid with deuterated buffer. We used small-angle X-ray scattering and cryoelectron microscopy reconstructions to determine the initial structural input parameters for intracapsid DNA, which allows accurate modeling of our SANS data. As result, we show a temperature-dependent density transition of intracapsid DNA occurring between two coexisting phases-a hexagonally ordered high-density DNA phase in the capsid periphery and a low-density, less-ordered DNA phase in the core. As the temperature is increased from 20 °C to 40 °C, we found that the core-DNA phase undergoes a density and volume transition close to the physiological temperature of infection (~37 °C). The transition yields a lower energy state of DNA in the capsid core due to lower density and reduced packing defects. This increases DNA mobility, which is required to initiate rapid genome ejection from the virus capsid into a host cell, causing infection. These data reconcile our earlier findings of mechanical DNA transition in phage.

Structural optical design of multi-group, high zoom ratio optical systems

In this paper, we propose a method for the structural optical design of multi-group, high zoom ratio optical systems based on matrix optics and Particle Swarm Optimization (PSO) algorithm. This method effectively addresses the problems of initial structural calculation difficulties, large volume, and unsmooth zoom curves with large inflection points in high zoom ratio optical systems. To design the zoom optical system, the matrix equations of the multi-group zoom system are derived using geometric optics; and a mathematical model is built to solve the initial structural parameters of the zoom system based on the matrix. Then, a new fitness function is introduced as an indicator to iteratively optimize the initial structural parameters of the system in multi-dimensional space, considering factors such as maximum zoom ratio, total optical length, and full field of view angle. Finally, this method is validated in two complex optical system designs including a 20x four-group and a 35x five-group zoom optical system, showing strong retrieval capabilities. Independent of traditional trial-and-error investigations for solutions, our method facilitates the automatic intelligent design of complex optical systems.

Design of the dual-band shared-aperture asynchronous zoom optical system using focus tunable lenses.

To meet the increasing demand of the current market and the diversity of application scenarios, combine the zoom system and the multi-band shared-aperture system, and fully harness their respective advantages, this paper proposes a dual-band shared-aperture asynchronous zoom optical system using focus tunable lenses (FTLs). To address the lack of available patents for such systems, we designed a sub-system simultaneous iterative optimization algorithm to calculate the initial structure parameters. This synchronous iterative optimization approach can strengthen the connection between sub-systems and compensate for the shortcomings of current mainstream design methods. The initial structure constructed in this way has a good performance in terms of structural stability and optimization potential. Based on these methods, we successfully designed an optical system that can work in both VIS and NIR bands, and the two sub-systems can zoom independently. The design results possess good performance in terms of distortion control, aberration correction, and volume control.

Effect of Organic Matter Components on the Mechanical Properties of Cemented Soil.

The organic matter in soft clay tends to affect the properties of cement-stabilized soil. The influence degree of different organic matter varies. In this paper, the influence weights and mechanism of the main organic matter components fulvic acid and humic acid on the mechanical properties of cemented soil were investigated. Impacts of FA/HA (fulvic acid/humic acid) values and curing time on the unconfined compressive strength, deformation characteristics, and microstructure of cemented soil were explored through the unconfined compressive strength test and electrical resistivity test. The results show that with the increase of FA/HA, the unconfined compressive strength of cemented soil gradually decreased and the plastic properties enhanced. The increase in curing time changed the stress-strain relationship of cemented soil, and some specimens showed brittle damage. The initial resistivity and structural property parameters of cemented soil gradually decreased with the increasing FA/HA value and increased with the increase of curing time. It revealed the influence law of FA/HA and curing time change on the microstructure of cemented soil. Based on the experimental results, the quantitative relationship equations between FA/HA and curing time and unconfined compressive strength, failure strain, deformation modulus, and resistivity were established.

Design method of dual-band synchronous zoom optical system based on co-path zoom groups

The dual-band zoom imaging system has great application value in military and civilian fields with the advantages of a large field of view (FOV) search, long-range tracking, camouflaged target reconnaissance, and all-day operation. To address the problem of synchronous zoom in dual-band co-aperture zoom optical systems, a dual-band simultaneous zoom optical system design method based on the co-path zoom groups is proposed. This optical system can realize zooming simultaneously in visible (VIS) and shortwave infrared (SWIR) bands and effectively control the total length. We first analyze the synchronous zoom principle of the dual-band co-path zoom optical system, then we propose a joint solution method for solving the initial structure of the dual-band zoom optical system. After obtaining the initial structure parameters, we performed the real-lens replacement and aberration correction in Zemax. Finally, a dual-band co-path simultaneous zoom optical system with working bands of 900∼1700 nm and 480∼660 nm, and zoom ranges of 10∼150 mm and 100∼150 mm, respectively, was designed. The focal length difference of the dual-band optical system is less than 0.16% during the simultaneous zooming process, and the system also has the advantages of good imaging quality, compact structure, simple zoom structure, and smooth cam curve.

Optimization Design of Large-Aperture Primary Mirror for a Space Remote Camera

Lightweight, high stability, and high-temperature adaptability are the primary considerations when designing the primary mirror of a micro/nano satellite remote sensing camera. In this paper, the optimized design and experimental verification of the large-aperture primary mirror of the space camera with a diameter of Φ610 mm is carried out. First, the design performance index of the primary mirror was determined according to the coaxial tri-reflective optical imaging system. Then, SiC, with excellent comprehensive performance, was selected as the primary mirror material. The initial structural parameters of the primary mirror were obtained using the traditional empirical design method. Due to the improvement of SiC material casting complex structure reflector technology level, the initial structure of the primary mirror was improved by integrating the flange with the primary mirror body design. The support force acts directly on the flange, changing the transmission path of the traditional back plate support force, and has the advantage that the primary mirror surface shape accuracy can be maintained for a long time when subjected to shock, vibration, and temperature changes. Then, a parametric optimization algorithm based on the mathematical method of compromise programming was used to optimize the design of the initial structural parameters of the improved primary mirror and the flexible hinge, and finite element simulation was conducted on the optimally designed primary mirror assembly. Simulation results show that the root mean square (RMS) surface error is less than λ/50 (λ = 632.8 nm) under gravity, 4 °C temperature rise, and 0.01 mm assembly error. The mass of the primary mirror is 8.66 kg. The maximum displacement of the primary mirror assembly is less than 10 μm, and the maximum inclination angle is less than 5″. The fundamental frequency is 203.74 Hz. Finally, after the primary mirror assembly was precision manufactured and assembled, the surface shape accuracy of the primary mirror was tested by ZYGO interferometer, and the test value was 0.02 λ. The vibration test of the primary mirror assembly was conducted at a fundamental frequency of 208.25 Hz. This simulation and experimental results show that the optimized design of the primary mirror assembly meets the design requirements of the space camera.

Adhesion Properties and Stability of Non-Polar Polymers Treated by Air Atmospheric-Pressure Plasma.

Atmospheric-pressure plasma (APP) has advantages for enhancing the adhesion of polymers and has to provide uniform, efficient treatment, which also limits the recovery effect of treated surfaces. This study investigates the effects of APP treatment on polymers that have no oxygen bonded in their structure and varying crystallinity, aiming to assess the maximum level of modification and the post-treatment stability of non-polar polymers based on their initial structure parameters, including the crystalline-amorphous structure. An APP reactor simulating continuous processing operating in air is employed, and the polymers are analyzed using contact angle measurement, XPS, AFM, and XRD. APP treatment significantly enhances the hydrophilic character of the polymers, with semicrystalline polymers exhibiting adhesion work values of approximately 105 mJ/m2 and 110 mJ/m2 for 0.5 s and 1.0 s exposure, respectively, while amorphous polymers reach approximately 128 mJ/m2. The maximum average oxygen uptake is around 30%. Short treatment times induce the roughening of the semicrystalline polymer surfaces, while the amorphous polymer surfaces become smoother. The polymers exhibit a limit to their modification level, with 0.5 s exposure being optimal for significant surface property changes. The treated surfaces remain remarkably stable, with the contact angle only reverting by a few degrees toward that of the untreated state.

A novel analytical model for porosity-permeability relations of argillaceous porous media under stress conditions

Argillaceous rocks, such as sandstones, shales, and mudstones, are widely distributed in nature and constitute approximately 50% of the global sedimentary rocks. They are the conventional reservoir rocks for hydrocarbon resources. To better characterize hydrocarbon resources, it is essential to understand the fundamental physical properties of argillaceous porous media (APM), and one of the most crucial properties is the porosity-permeability relationship (PPR). However, due to the enormous complexity of pore structures in APM, the effects of relevant factors on PPR remains unclear, and the major factors controlling PPR are still open questions. In this work, experimental tests were carried out on 43 artificial argillaceous sandstone samples to evaluate the porosity and permeability relations under stress dependence. An analytical model was then proposed to interpret the experimental results. The analytical solutions are consistent with the experimental data and the simulation results obtained from the Lattice Boltzmann method. It indicates that the derived model can precisely capture the PPR of APM. The analysis results show that the PPR of APM under stress dependence is related to clay volume content, effective stress, initial irreducible water saturation, rock lithology, and pore structure parameters (e.g., the maximum pore radius, the minimum pore radius, pore fractal dimension and tortuosity fractal dimension). These findings can enhance the understanding of the PPR and coupled flow-deformation behavior in APM and set the stages for a proper investigation of PPR in APM.

The study of the dynamics of clinical and laboratory-instrumental parameters in hypertensive patients with obesity who underwent COVID-19-associated pneumonia

BACKGROUND : According to the results of the ESSE-RF study, the frequency of obesity in the population reached 29.7%. Obesity is one of the main risk factors for the development of cardiovascular diseases. Features of the course of COVID-19 in patients with obesity is a very urgent problem. AIM : The aim of the study was a comparative investigation of clinical and laboratory-instrumental parameters in AH patients with or without obesity who had COVID-19 associated pneumonia, to identify the role of obesity as a potential predictor of post-COVID cardiovascular complications 3 months after discharge from the hospital. MATERIALS AND METHODS : Materials and methods. The study included 174 patients with COVID-19-associated pneumonia. Group 1 included 78 patients with AH without obesity, group 2 — 96 patients with AH and obesity. All patients were tested with a blood sample at the time of admission and 3 months after discharge from the hospital. We assessed parameters of general blood test, biochemistry, hemostasis, inflammation biomarkers — concentration of C-reactive protein (CRP), highly sensitive CRP (hs-CRP), homocysteine, IL-6, etc. All patients initially underwent computed tomography of the chest. In both groups, 24-hour blood pressure monitoring was performed using BPLaB device, according to the standard protocol; echocardiography using an expert class ultrasound diagnostic system Vivid S70. The study is registered with the Clinical Trials.gov database Identifier: NCT04501822. RESULTS : Results. The biomarker that significantly distinguished the both groups of patients, as well as subgroups according to the degree of obesity was the concentration of maxCRP and hs-CRP, which was significantly higher in group 2. In addition, the registered maximum values of MPO, NT-proBNP, IL-1,6, TNA-α and NRL parameters in group 2 of patients with 2–3 degrees of obesity, may indicate the highest probability of developing delayed adverse cardiovascular complications in this group of patients. Mean systolic blood pressure, variability of systolic and diastolic blood pressure, and heart rate at night were significantly higher in AH patients with obesity. Numerous correlations of obesity with laboratory and instrumental parameters have been registered, which may indicate an increased likelihood of delayed unwanted cardiovascular complications in this particular group of patients. Multiple regression showed that obesity is an independent predictor of an increase in LDH, hs-CRP and right atrium. CONCLUSION : Dynamic control of the studied parameters in patients with AH and OB registered an increased concentration of CRP at the initial stage and 3 months after treatment, with a general trend towards a decrease in the increased initial structural parameters of ECHO CG. The logistic regression method showed that the presence of OB in patients with AH is an independent factor causing increased levels of immune inflammation (CRP), a marker of tissue destruction (LDH), and load on the right atrium.

Staggered compensation of a multi-tube load curve with height difference and variable induced ring distribution

To solve the problem of high energy absorption conflicting with small load fluctuation, a multi-tube combined energy absorption structure with induced ring based on the load curve staggered compensation strategy was proposed. The effects of the number, height, and thickness of the induced rings on the load curve trend were investigated by experiment and simulation, and the initial structural parameters suitable for the design of load curve staggered compensation. were determined. Then, the influences of height difference and induced ring distribution on the load curve trend were revealed, and the control method that can make the appropriate difference in each tube load curve was summarized. Moreover, the diagram of the correlation between the key multi-tube combination parameters and the load curve control effect was plotted based on classical theory and the acquired temporal influence. Finally, a multi-tube structure with suitable height difference and variable induction ring distribution was proposed. Compared with the multi-tube structure with the same configuration parameters, the combined structure proposed in this study decreases the initial peak and load fluctuation by 49.45% and 58.93%, respectively, while maintaining a high energy absorption.

Mechanical Properties of In Situ Loess under Different Combined Water State Macroscopic and Mesoscopic Studies

To study the mechanisms of strong and weak combined water on the mechanical properties of in situ loess deformation and strength, triaxial compression tests with different combined water contents were carried out to in situ loess in a region of Shaanxi Province, China. The influence on the mechanical properties and structural variation of in situ loess was discussed from the perspective of combined water. The endogenous factors of deformation and strength properties of in situ loess in triaxial tests were investigated from a fine-scale perspective by combining numerical simulations of discrete elements. The results show that the failure specimen under the condition of strong combined water has an obvious shear band and shows brittle failure. The failure mode of soil samples under weak combined water is characterized by no obvious cracks and bulging, which is plastic failure. The water content at the boundary of strong and weak combined water is the boundary to distinguish weak and strong strain hardening. With the increase of combined water, the ultimate strength, the structural strength, and structural parameters decrease, and the initial structural parameters decrease nonlinearly, resulting in the decrease of soil structure and deformation resistance. Weak combined water is the main factor affecting soil structure. The particle flow numerical simulation explains the whole process of triaxial test of in situ loess from macro to meso and explains from the meso perspective that the structural strength change of intact loess under different combined water contents is mainly caused by the change of contact force and pore between particles.

Electrochemical Behavior of Reinforced Concrete Beams with Different Flexural Tensile Stresses in the Steel Reinforcement

In this work, the electrochemical and structural behavior of reinforced concrete beams subjected to flexure is studied. Eight beams with and without corrosion were considered. The study variable was the tensile stress in the longitudinal steel reinforcement. Stresses of 40% and 80% of the yielding stress of steel were considered. The beams were subjected to sustained loads using a post-tensioning system. Corrosion in the steel reinforcement was induced by chloride contamination of fresh concrete and wet and dry cycles. The corrosion rate of the steel, as well as the resistivity and concentration of chlorides of the concrete, were measured. The beams were tested two times using a four-point loading system. The first one before that corrosion was induced; a load associated with the target tensile stress in the steel reinforcement was applied to determine the initial structural parameters of the beams: crack pattern, crack resistance, and initial and postcrack stiffness. The second time after the corrosion was induced; incremental loads were applied until the failure of beams to determine the change in yielding and maximum strength, as well as the postyielding stiffness of the beams. It was found that the electrochemical behavior of the beams with corrosion was similar regardless of the tensile stress in the steel considered (40% or 80%). The measured electrochemical parameters indicated a high level of corrosion in accordance with Mexican standards; however, from the structural point of view, the strength and stiffness were not significantly affected by the corrosion status. Beams with electrochemical parameters associated with a higher level of corrosion are needed to study the initial degradation of the structural parameters, for example, strength degradation.

Design and Multi-Objective Optimization of a Composite Cage Rotor Bearingless Induction Motor

To improve the quality of starting torque and suspension force, a composite cage rotor bearingless induction motor (CCR-BIM) is designed, which adopts a composite cage rotor structure that combines an inner rotor and an outer rotor. First, the overall structure of the CCR-BIM is designed, the composite cage rotor of the CCR-BIM is specially designed and analyzed for the induction principle, and the mathematical model of suspension force and torque is deduced. Second, the initial structural parameters are determined, and motor qualities, such as starting torque quality and suspension force quality, are compared and analyzed between the proposed motor and BIM using a finite element model (FEM). Third, based on the response surface model (RSM), a multi-objective improved NSGA-II is constructed, and the three optimization objectives of starting torque, suspension force, and suspension force pulsation are optimized. Finally, the results of the experimental setup prove that the starting torque increases by 6.98%, the suspension force increases by 5.45%, and the suspension force pulsation decreases by 18.54%. The effectiveness of the proposed motor and the correctness of the multi-objective optimization strategy are verified.

Design and theoretical analysis of the image-side telecentric zoom system using focus tunable lenses based on Gaussian brackets and lens modules

For now, telecentric system and zoom system have been extensively implemented in machine vision, industrial inspection, etc. However, studies on optical systems with both telecentric and zoom functions are still rare. To improve this situation, we present the design method of the telecentric zoom system with four focus tunable lenses (FTL) and a moving aperture stop (STOP) by applying Gaussian brackets and lens modules. We first improve the Gaussian brackets to achieve the initial parameter solution of the telecentric zoom FTL system, then we introduce a selection method to find the initial structural parameters with sufficient potential for optical design. After that, we use the lens module method to design the initial structure of the optical system, we also expand the combination method of the lens modules which contains an FTL. Finally, the initial structures of a 4X image-side telecentric zoom FTL system are constructed as an example and then optimized using CODEV. As a result, we get an image-side telecentric zoom FTL system with an F/# of 4, a zoom range of 20 mm to 80 mm, an image plane size of 8 mm, and a total length of 218 mm, which performs well in telecentricity control, distortion control, and aberration correction.