Experimental study on dynamic performance of pneumatic flexible manipulator with single degree of freedom

Aiming at the problem of insufficient transverse stiffness of flexible manipulator, a kind of pneumatic flexible manipulator with single degree of freedom is developed by using elongated pneumatic artificial muscle joint as the actuator. The structure and functional principle of the manipulator are introduced. The dynamic experiment of the manipulator was carried out by using the three-dimensional motion measurement system, and the dynamic characteristics of the manipulator under three different incentive signals (step, pulse and ramp ) were analyzed, which provided a basis for the establishment of the manipulator control model in the later stage

Effects of different inlet velocity on the polishing quality of abrasive flow machining

In order to study the effect of different inlet velocity on the polishing quality of abrasive flow machining, this paper takes the variable diameter pipe as an example. The fluid dynamic pressure and total energy of abrasive particles under coupling field with different inlet velocities were carried out by using computational fluid dynamics software. The results of numerical analysis show that the polishing quality becomes better with the increase of the inlet velocity. At the same inlet velocity, the smaller the pipe diameter is, the higher the polishing quality will be. Therefore, the optimum inlet velocity can be selected by numerical simulation according to the size of the aperture of workpiece in the actual processing, which can provide technical support for the production

Literature review of condensation and evaporation of R290

Nowadays, an increasing attention in environmental issues including the global warming effect and ozone layer depletion has been attracted. R22 is urged to be ruled out until 2020 and 2030 for developed and developing countries. R290 (propane) has been regarded as a promising alternative refrigerant for the air-conditionings. Comparing to other alternatives, R290 has zero ozone depletion potential and negligible GWP. However, R290 has different thermo-physical properties than conventional refrigerants and it would influence the application in tubes such as shear forces, gravity and surface tension. The condensation and evaporation behavior of R290 would has a great effect in designing suitable heat exchanger for R290. In recent years, researchers have made great efforts in studying different working fluids behaviors and multiple semi-empirical correlations have been established to predict the heat transfer and pressure drop. However, the study about R290 behavior is very limited. According to the past experiences in condensation and evaporation studies, the semi-empirical models may be not very accurate in the working conditions outside the range where they are established. This paper presents a detailed review of research work done on the condensation and evaporation of R290. It also gives a comparison between R290 and other working fluid behavior and makes a summarization on predicting correlations for R290 heat transfer and pressure drop. This paper is a starting point for future R290 studies and R290 applications in air conditioning systems.

Numerical analysis of the influence of abrasive concentration on the quality of baffle servo valve in abrasive flow machining

In order to analyze the effect of abrasive concentration on the quality of abrasive flow machining, this paper takes the baffle servo valve as the research object and carries out numerical analysis of solid-liquid two-phase abrasive flow machining process. By analyzing the static pressure and velocity fields of nozzle orifices in baffle servo valves under different abrasive concentration conditions, it is found that abrasive flow has the best precision machining effect when the abrasive concentration is 10 %. And the best quality area for abrasive flow machining is in the small hole. The study shows that the larger the abrasive concentration is, the better the quality of abrasive flow machining is

Optimization of sub-grid scale model for abrasive flow machining curved tube based on large eddy simulation

Abrasive flow machining technology is a new type of precision machining technology. Due to its unique rheological properties, it can process any complex structure and size parts to meet the requirements that conventional machining cannot meet. Combined with the turbulent flow characteristics of the abrasive flow, the large eddy simulation numerical method is used to simulate the machining process of the abrasive flow. The influence of different sub-grid scale models on the simulation results is discussed. Taking curved tube as the research object, the static pressure, dynamic pressure and velocity of different sub-grid models are analyzed to find the best sub-grid scale model. Large eddy simulation method is used to simulate the complex flow channel parts, and the best sub-grid scale model suitable for complex flow channels is determined, which reveals the grinding and polishing rule of abrasive flow and provides academic support for future research. Therefore, it has frontier and important research value

Experimental study on the static properties of single dimensional bidirectional bending joint

In order to increase the lateral stiffness of the joint, a new kind of single-dimensional bidirectional bending joint was developed. Based on the equilibrium analysis of force and moment of the joint and considering the influence of the joint deformation law, the static bending theoretical model of the joint was established. The experimental system was set up to carry out bending experimental. The experimental results show that the experimental data of the joint are consistent well with the theoretical data. The bending deformation has a good consistency of swinging angle from left to right. At 0.35 mPa, the bending angle of the angle reaches 57.5°, which can be used as elbow or knee joints in bionic machinery

LCCP Analysis of Energy-Saving Effect of Defaulting to Recirculated Cabin Air in EV Mobile Air Conditioning System

The climate control load is the most significant auxiliary loads present in vehicles today. The peak climate control load of an AC system in sedan can be as large as the engine input power. As the attention on vehicle energy economy is rising worldwide, the energy-saving of mobile air conditioning is becoming more and more important. Most mobile AC systems nowadays draw air from outside the vehicle and cool it to the desired comfort level inside the vehicle. Lots of energy is wasted during this process due to continuously cooling the hotter outside air instead of cooling the “cooler†inside air. Compared to that, defaulting to recirculated cabin air will certainly be energy-saving. Though some studies have revealed the energy saving effectiveness under bench test conditions, it is still unclear how much energy can be saved when mobile AC systems are operated in different climates and driving patterns. The GREEN-MAC-LCCP tool is modelled to evaluate the life cycle climate performance of mobile AC system, and it is well-accepted. This tool is capable of analysing the full cycle of greenhouse gas emissions (GHG) of alternative refrigerant systems and different system structures. In this article, the energy-saving effect of defaulting to recirculated cabin air is evaluated using GREEN-MAC-LCCP. It is found that 7%-48% of energy saving can be achieved under the calculated climate conditions

Kinematics analysis on pneumatic flexible finger

Based on flexible pneumatic joints, a new kind of flexible finger was proposed. The structure and operating principle of the finger was presented. The kinematics equation of the finger was built by homogeneous transformation matrix. Based on the static experiment of joints, the kinematic simulation of the finger was carried out and the motion trajectory of the finger was obtained. The simulation results show that the finger has good flexibility and can complete the functions of forward bending, reverse bending and lateral swing of human hand

Establishment of linkage phase, using Oxford Nanopore Technologies, for preimplantation genetic testing of Coffin-Lowry syndrome with a de novo RPS6KA3 mutation

Background: This study aimed to perform preimplantation genetic testing (PGT) for a female Coffin-Lowry Syndrome (CLS) patient with a de novo mutation (DNM) in RPS6KA3. It was challenging to establish the haplotype in this family because of the lack of information from affected family members. Hence, we explored a new and reliable strategy for the detection of the DNM in PGT, using Oxford Nanopore Technologies (ONT) and the MARSALA platform.Methods: We performed whole-exome sequencing (WES) on the proband and confirmed the pathogenic mutation by Sanger sequencing. The proband then underwent PGT to prevent the transmission of the pathogenic mutation to her offspring. We diverged from the conventional methods and used long-read sequencing (LRS) on the ONT platform to directly detect the mutation and nearby SNPs, for construction of the haplotype in the preclinical phase of PGT. In the clinical phase of embryo diagnosis, the MARSALA method was used to detect both the SNP-based haplotype and chromosome copy number variations (CNVs), in each blastocyst. Finally, a normal embryo was selected by comparison to the haplotype of the proband and transferred into the uterus. Sanger sequencing and karyotyping were performed by amniocentesis, at 17 weeks of gestation, to confirm the accuracy of PGT.Results: Using WES, we found the novel, heterozygous, pathogenic c.1496delG (p.Gly499Valfs*25) mutation of RPS6KA3 in the proband. The SNP-based haplotype that was linked to the pathogenic mutation site was successfully established in the proband, without the need for other family members to be tested with ONT. Eight blastocysts were biopsied to perform PGT and were assessed with a haplotype linkage analysis (30 SNP sites selected), to give results that were consistent with direct mutation detection using Sanger sequencing. The results of PGT showed that three of the eight blastocysts were normal, without the DNM. Moreover, the patient had a successful pregnancy, after transfer of a normal blastocyst into the uterus, and delivered a healthy baby.Conclusion: The ONT platform, combined with the MARSALA method, can be used to perform PGT for DNM patients without the need for other samples as a reference