Pneumatic Lines Research Articles

Mathematical modeling of drives with tandem pneumatic cylinders

The article considers the issue of mathematical modeling of tandem pneumatic cylinders. Despite the fact that the mathematical description of the operation of drives with single-piston cylinders is considered in sufficient detail in the literature, the peculiarity of drives with tandem cylinders, namely the commutation of their working cavities with pneumatic discharge and exhaust lines through one pneumatic distributor, requires the formation of a certain approach to their mathematical description. The paper shows two developed versions of mathematical models that describe their work. The first option involves taking into account some conventional intermediate chambers behind the pneumatic distributor, where the division and combination of compressed air flows between the pneumatic distributor and the working cavities of the tandem pneumatic cylinder takes place. The second one (the simplified) considers the working cavities of the cylinder independently. Comparison of the results of mathematical modeling for two options showed a fairly significant difference in the time of movement of the piston of the cylinder. Moreover, it can be seen from the results that this difference is primarily associated with the distribution of air pressure between the intermediate chambers and the working cavities of the cylinder. According to the obtained results, it follows that when developing pneumatic drives and pneumatic actuators with tandem pneumatic cylinders, despite the complexity of the calculation, it is preferable to take into account in the mathematical model the intermediate chambers, where the division and combination of compressed air flows takes place. The developed model can be used in the design of pneumatic drives of various machines and mechanisms that use tandem pneumatic cylinders. This modeling approach can be used in the study of other multi-piston pneumatic engines or drives with several engines controlled by a single pneumatic switchgear.

Analysis and Design of Tamper-Mitigating Microfluidic Routing Fabrics

Microfluidic routing fabrics are reconfigurable primitives that permit the dynamic redirection of fluids on a flow-based microfluidic biochip. Such primitives are bringing the benefits of rapid prototyping and on-the-fly reconfigurability from integrated circuits to the microfluidic domain. An unfortunate side effect of this increased flexibility is susceptibility to tampering. A malicious adversary can alter either the electronic control signals or the pneumatic control lines used to drive the routing fabric. In this paper, we provide a high-level security assessment of microfluidic systems utilizing routing fabrics, and analyze their security under actuation tampering attacks. We show that under reasonable assumptions, the permissible states of a routing fabric form a probability distribution. We provide methods for efficiently determining this distribution through a binary tree representation. We then show how to synthesize routings fabrics that exhibit well-defined behaviors. We call a routing fabric designed in such a way tamper-mitigating , as it makes the effects of tampering probabilistically less severe. We then show how the proposed methodology can be used to protect a forensic DNA barcoding application from attack.

High-throughput microstructure printing technology using inflatable thin membrane with microchannel

Low-cost manufacturing technology for a micro-sized structure is receiving a lot of attention as human society is getting mixed with sensors and electronics. A template printing technology which forms micro-patterns by letting ink dried within a solvent permeable template is an attractive alternative of traditional costly micro-fabrication. However, low printing speed and lack of scalability have been recognized as a major drawback of this method. Here, we propose a novel printing machine using an inflatable polymer template. It is expected that thin membrane improves the printing speed due to its high permeation speed; however, the theoretical prediction and experimental proof of this approach has not been studied. A 450-μm thick membrane is fabricated by the casting polydimethylsiloxane (PDMS) on a silicon master mold, fixed to a printer head, and inflated to contact with substrate uniformly. The permeation mechanism is investigated by using both of the numerical simulation and experiments and discovers that the diffusion in thin membrane obeys an analytical solution for Fick’s diffusion in steady state, while a conventional bulk template (10 mm) is in non-steady state. The printing system composed of pneumatic lines, a flash sintering unit, and a printer head holds the membrane is prototyped to ensure reproducibility of this novel method, five times faster printing speed compared to the ordinal method is confirmed.

Direct 3-D Imaging Based on Parallel-Helical ECT

Multiphase flows in annular pipes have important applications, such as in the drilling pipes in the oil industry and some pneumatic transport lines. Due to the complexity of the flow patterns, more advanced measurement techniques will be needed to see more insights. In this paper, phase distribution in an annular space is visualized by means of 3-D electrical capacitance tomography (ECT). A sensor with a double helical electrode arrangement is developed to facilitate 3-D measurement. The sensitivity map of the sensor is generated via inner product of the values of the electric fields generated by the finite-element methods. Landweber algorithm is used to reconstruct the ECT images. An experimental platform of multiphase flow detection using the 3-D ECT is built and measurements of different material distributions are made. The experimental results show that this technology can identify the shapes and positions of the working medium in the sensor.

Characterization of calcium looping sorbents with a novel twin bed reactor

The experimental characterization of sorbents for Calcium Looping (Ca-L) processes is generally accomplished by thermogravimetric analysis or by using single fluidized bed bench scale reactors. These methods may present limitations, the most significant being the poor ability to reproduce the thermal history that sorbent particles experience in a real Ca-L plant. This limitation may severely affect the correct evaluation of the sorbent behavior in terms of CO2 capture capacity and attrition. In this study, a purposely developed experimental apparatus is applied for Ca-based sorbent testing under conditions that simulate a realistic thermal history of the sorbent. The apparatus consists of two identical lab-scale bubbling beds (Twin Beds - TB) operated batchwise as the calciner and the carbonator, respectively. The reactors are connected to each other via a rapid solids pneumatic transfer line, designed so as to enable rapid and selective transfer of the sorbent from one reactor to the other at the end of each calcination/carbonation stage. The two beds consist mostly of coarse-grained silica sand, acting as a thermal ballast, to which sorbent samples to be characterized are added.The TB apparatus has been used to investigate the effect of the thermal history on the performance of two limestones, in terms of CO2 capture capacity and attrition tendency, upon multiple calcination/carbonation cycles under the typical operating conditions of the Ca-L process. The results have been compared with those obtained for the same sorbents carried out in a single lab-scale fluidized bed reactor (SB) and under the same operating conditions. The comparison showed that the CO2 capture capacity in the TB system is larger than that found in SB tests for both sorbents. On the contrary, the absence of strong thermal shocks in the TB experiments leads in general to a decrease of the attrition tendency, with a reversal in terms of generated fines between calcination and carbonation stages. Indeed, the generation rate of fines measured in the TB tests during carbonation is smaller than that measured in the corresponding calcination stage, which is opposite to what was found during the tests in the SB device. These findings indicate that the sorbent thermal history plays a non-negligible role on its CO2 capture performance in Ca-L.

An Asymptotically Stable Pressure Observer Based on Load and Displacement Sensing for Pneumatic Actuators With Long Transmission Lines

Pneumatic systems have regained popularity in robotics with the new advances in the electronic valves that have enabled precise position control of pneumatic cylinders. Recently, the use of pneumatic systems has been extended to force and impedance control. Such new applications include teleoperated medical robotic systems with pneumatic transmission lines where more advanced system modeling and control is required. Pressures of a pneumatic actuator are commonly used to improve control performance. When direct pressure measurement is not available or not desirable for cost-effective implementation, actuator pressures can be estimated by a model-based observer. This paper introduces a nonlinear pressure observer based on force and displacement sensing. The proposed algorithm allows for asymptotic stability of pressure estimation error with an improved convergence. The presented method does not require a transmission line model and guarantees bounded stability in the presence of disturbance in force measurements, hence it is able to provide a robust pressure estimation. The effectiveness of the proposed observer is confirmed by performing force control experiments in a teleoperated pneumatic system.

Physical modelling of a long pneumatic transmission line: models of successively decreasing complexity and their experimental validation

ABSTRACTThere exist a significant number of models, which describe the dynamics of pneumatic transmission lines. The models are based on different assumptions and, thereby, vary in the physical phenomena they incorporate. These assumptions made are not always stated clearly and the models are rarely validated with measurement data. The aim of this article is to present multiple distributed parameter models that, starting from a physical system description, successively decrease in complexity and finally result in a rather simple system representation. Data, both from simulation studies as well as from a pneumatic test bench, serve as a quantitative validation of these assumptions. Based on a detailed discussion of the different models, this article aims at facilitating the choice of an appropriate model for a given task where the effect of long pneumatic transmission lines cannot be neglected and a trade-off between accuracy and complexity is required.

Combined Adaptive and Predictive Control for a Teleoperation System with Force Disturbance and Input Delay

This work presents a new discrete-time adaptive-predictive control algorithm for a system with force disturbance and input delay. This scenario is representative of a mechatronic device for percutaneous intervention with pneumatic actuation and long supply lines which is controlled remotely in the presence of an unknown external force resulting from needle-tissue interaction or gravity. The ultimate goal of this research is the robotic-assisted percutaneous intervention of the liver under Magnetic Resonance Imaging (MRI) guidance. Since the control algorithm is intended for a digital microcontroller, it is presented in the discrete-time form. The controller design is illustrated for a 1 degree-of-freedom (DOF) system and is conducted with a modular approach combining position control, adaptive disturbance compensation, and predictive control. The controller stability is analyzed and the effect of the input delay and of the tuning parameters is discussed. The controller performance is assessed with simulations considering a disturbance representative of needle insertion forces. The results indicate that the adaptive-predictive controller is effective in the presence of a variable disturbance and of a known or variable input delay.

Determination of length of horizontal pneumatic transport line in drilling machine for mud removal by negative pressure

Under discussion is soil transport by negative pressure generated in horizontal rotating pipeline. Based on the relations between soil batch velocity, soil batch mass and diameter of the pipeline, the authors have developed procedure to determine the limit pipeline length. The rotary velocity of the pipeline is related with its diameter. Reliability of the proposed procedure results is experimentally proved.

Разработка средств индивидуальной защиты персонала, работающего в боксах, оборудованных пневмолинией

Objective of the study is to demonstrate technical and operational characteristics of the specialized suit, its protective efficacy in relation to respiratory organs and skin at different air-injection rates through analyzing the possibility to utilize individual protective equipment, connected to pneumatic line, from the viewpoint of biological safety. Materials and methods. Tested has been specialized suit of a combined type. Investigations have been conducted in an aerosol cabinet, involving volunteer researches, who performed controlled medium physical activities within 4 hours term. In the course of the studies analyzed have been the following physical parameters of the test operators: heart rate, respiratory rhythm, body temperature. Identification of layer-by-layer contamination of the specialized suit (external and internal surfaces), linen and skin of the volunteers has been carried out applying washing techniques and triple agar prints. Results and conclusions. Testing of the designed suit has revealed that its utilization provides for proper solid protection of healthcare personnel from microbial aerosol, and adherence to desired speed of air-injection into interlayer (under-suit) space, ≥ 250 l/min, allows for maintaining high working capacities.

A pneumatic pressure-driven multi-throughput microfluidic circulation culture system.

Here, we report a pneumatic pressure-driven microfluidic device capable of multi-throughput medium circulation culture. The circulation culture system has the following advantages for application in drug discovery: (i) simultaneous operation of multiple circulation units, (ii) use of a small amount of circulating medium (3.5 mL), (iii) pipette-friendly liquid handling, and (iv) a detachable interface with pneumatic pressure lines via sterile air-vent filters. The microfluidic device contains three independent circulation culture units, in which human umbilical vein endothelial cells (HUVECs) were cultured under physiological shear stress induced by circulation of the medium. Circulation of the medium in the three culture units was generated by programmed sequentially applied pressure from two pressure-control lines. HUVECs cultured in the microfluidic device were aligned under a one-way circulating flow with a shear stress of 10 dyn cm(-2); they exhibited a randomly ordered alignment under no shear stress and under reciprocating flow with a shear stress of 10 dyn cm(-2). We also observed 2.8- to 4.9-fold increases in expression of the mRNAs of endothelial nitric oxide synthase and thrombomodulin under one-way circulating flow with a shear stress of 10 dyn cm(-2) compared with conditions of no shear stress or reciprocating flow.

Exergy analysis of the pneumatic line throwing system

Energy efficiency is an important property in pneumatic systems. There are three approaches for evaluating the efficiency of pneumatic systems. The analysis shows that exergy-related analysis is the most suitable tool. In this study, exergy analysis is performed in a pneumatic line throwing system. The non-flow exergy based on the real gas equation is deduced and divided into the volume component and the non-volume component. The results show that the total exergy efficiency of the system fluctuates slightly between 16.29% and 16.86%. The exergy efficiency of the throttling decompression process decreases from 97.12% to 67.34% as the working pressure decreases. While the exergy efficiency of the pneumatic line-thrower part increases from 17.36% to 24.19% with the decreasing working pressure. Some practical measures are proposed to improve the efficiency of the system. Additionally, future work on this study and outlook for exergy analysis in pneumatic systems are discussed.

Exogenous Gene Integration for Microalgal Cell Transformation Using a Nanowire-Incorporated Microdevice.

Superior green algal cells showing high lipid production and rapid growth rate are considered as an alternative for the next generation green energy resources. To achieve the biomass based energy generation, transformed microalgae with superlative properties should be developed through genetic engineering. Contrary to the normal cells, microalgae have rigid cell walls, so that target gene delivery into cells is challengeable. In this study, we report a ZnO nanowire-incorporated microdevice for a high throughput microalgal transformation. The proposed microdevice was equipped with not only a ZnO nanowire in the microchannel for gene delivery into cells but also a pneumatic polydimethylsiloxane (PDMS) microvalve to modulate the cellular attachment and detachment from the nanowire. As a model, hygromycin B resistance gene cassette (Hyg3) was functionalized on the hydrothermally grown ZnO nanowires through a disulfide bond and released into green algal cells, Chlamydomonas reinhardtii, by reductive cleavage. During Hyg3 gene delivery, a monolithic PDMS membrane was bent down, so that algal cells were pushed down toward ZnO nanowires. The supply of vacuum in the pneumatic line made the PDMS membrane bend up, enabling the gene delivered algal cells to be recovered from the outlet of the microchannel. We successfully confirmed Hyg3 gene integrated in microalgae by amplifying the inserted gene through polymerase chain reaction (PCR) and DNA sequencing. The efficiency of the gene delivery to algal cells using the ZnO nanowire-incorporated microdevice was 6.52 × 10(4)- and 9.66 × 10(4)-fold higher than that of a traditional glass bead beating and electroporation.

Research of Integrated Valve Plate Differential Pressure Leak Measuring Device

Valve plate differential pressure leak measuring device uses channels in the plate instead of the pneumatic pipe lines in traditional leak measuring devices. The integrated device in this paper will integrate the whole leak measuring pneumatic system on a fixed valve plate through combining self-made valve plate and pneumatic valve, which will significantly reduce the cost, simplify the design of the differential pressure leak measuring pneumatic piping, make the operation more simple and improve the reliability and accuracy of leak measuring device. The pneumatic charging valve and the pneumatic release valve can work in both high and low pressure conditions, so the range of application is very wide and all these features will significantly improve the competitiveness of the differential pressure leak measuring device company.

Modelling and experimental validation of Textile Pockets based active inflatable device

This paper aims with the mathematical modelling of an active inflatable device. This device is composed of a compressor, an Electro-pneumatic Pressure Converter (EPC) and an Inflatable Textile fabric Pocket (ITP). The later has interesting mechanical properties and is fabricated using Jacquard knitting technique which allows automatic production of unlimited varieties of pattern weaving without any mould. Thanks to these features, these ITPs have provided a better alternative to the classical airbags made by stretchable polymer material. The proposed mathematical model is obtained by combining sub-models of two main parts of the whole system. In this way, a generalised and flexible model is obtained which can easily take into consideration the ITPs of different shapes. The pressure dynamics inside the ITP are considered by taking into account the air flow rate, variation of the volume of ITP and the length of pneumatic lines joining ITP with compressed air source. The parameters of the whole mathematical model are obtained via identification techniques. The effectiveness of the model is assessed through several experimental tests with the help of a servo hydraulic fatigue testing machine.

2A1-P06 空圧配管内音響通信を利用した空圧アクチュエータの多重空圧駆動システム : 第2報 圧縮空気を利用した自立電源の開発(アクチュエータの機構と制御(1))

Pneumatic actuators have been widely utilized in industrial machines with their advantages of low cost, safety, and high compliance. However, pneumatic systems need many air supply lines from a compressor, control lines from a controller, and power supply lines, making them complicated and large. This paper proposes a new control method reducing the number of control lines and power supply lines in pneumatic systems. It needs two key components; Multiplex Pneumatic Actuator Drive (MPAD) and Local Power Supply (LPS) for each local module. This paper deals with LPS from pneumatic line, firstly, we explain its outline design. Secondly, LPS is developed and is tested to confirm its performance. Thirdly, charging method is improved for high charging quantity. Finally, LPS is integrated into MPAD and they is shown that it reduces control lines and power supply lines in operational experiment.

Design, development, and evaluation of a master–slave surgical system for breast biopsy under continuous MRI

Magnetic Resonance Imaging (MRI) provides superior soft-tissue contrast in cancer diagnosis compared to other imaging modalities. However, the strong magnetic field inside the MRI bore along with limited scanner bore size poses significant challenges. Since current approaches in breast biopsy using MR images are primarily blind targeting approaches, it is necessary to develop an MRI-compatible robot that can avoid multiple needle insertions into the breast tissue. This MRI-compatible robotic system could potentially lead to improvement in the targeting accuracy and reduce sampling errors. A master–slave surgical system has been developed comprising a MRI-compatible slave robot which consists of one piezo motor and five pneumatic cylinders connected by long pneumatic transmission lines. The slave robot follows the configuration of the master robot, which provides an intuitive manipulation interface for the physician and operates inside the MRI bore to adjust the needle position and orientation and perform needle insertion tasks. Based on the MRI experiments using the slave robot, there was no significant distortion in the images, and hence the slave robot can be safely operated inside the MRI with minimal loss in signal-to-noise ratio (SNR). Ex vivo and in vivo experiments have been conducted to evaluate the performance of the master–slave surgical system.

Non-linear friction modelling and simulation of long pneumatic transmission lines

Dynamic modelling and numerical implementation strategies for fluid transmission lines have been studied thoroughly, mainly for the application in hydraulic pipeline networks. Recent interest in energy efficiency has seen a resurgence of this field for compressed air networks, with impact on manufacturing processes, simulation of pneumatic drive components, and other theoretical analysis applications. The effects of long tubes connecting system components are often neglected to increase computational speed and reduce model size. This document highlights existing modelling approaches from practice as well as from fluid dynamic theory. Existing approaches for hydraulic transmission lines are adapted to their use for pneumatic tubes. A low-order model is derived capable to predict the transient behaviour of pressure and mass flow rate distribution within the tube. The model accounts for non-linear turbulent flow conditions, and is designed to be compatible with signal-flow simulation programmes, increasing its usability in large-scale industrial settings. It is numerically well conditioned, and all parameters are determined by physical or empirical relationships. Both its transient and quasi-stationary behaviour are validated against experimental results.

Concerted operation of pneumatic percussion tool and air-aided chips removal line in horizontal hole drilling machines

The authors study work process of pneumatic percussion units with valveless air distribution under exhaust back pressure in drilled solid removal line in long horizontal hole drilling machines. It is shown that range of efficient values of the machine performance equal to maximum percussion force does not change under increase in the exhaust back pressure.

Experimental study of blown-abrasive decontamination of the inner surfaces of pipelines for a pulsed pneumatic conveyor model

A method of decontaminating the inner surface of pulsed pneumatic conveyer lines by removing contaminated metal by blowing an abrasive (liquid-free decontamination) is examined. The results of a study of the removal of a surface layer of metal as a function of the abrasive materials used are presented. These investigations were performed on a 1:7 scale pulsed pneumatic conveyer model.