Vacuum Generators Research Articles

Autonomous Pose Detection and Alignment of Suction Modules of a Biped Wall-Climbing Robot

Vacuum adsorption is a simple but effective attaching method widely used in many fields including robotic wall climbing. It is required that the sucker is aligned well with the target surface to form airtight chamber for vacuum generation. For applications in biped wall-climbing robots, automatically aligning the sucker with the wall is beneficial and important to enhance the efficiency and effectiveness of vacuum adsorption. Especially, such a function is essential for autonomous intelligent climbing. To this end, we propose a novel and low-cost approach to perform autonomous alignment of a sucker (suction module) based on noncontact sensors. We first develop a sensing system to detect the configuration of the swinging suction module with respect to the target surface, and then present an algorithm to compute the configuration transformation and control the robot to drive the suction cups toward the target surface with a well-aligned configuration for adherence. In this paper, the basic theory for autonomous pose detection and alignment of the suction module for wall climbing with a biped robot is presented. Specifically, the key configuration of the swinging suction module for adsorption is analyzed, and the pose detection model, the conditions for forming airtight chamber, and the autonomous alignment algorithm are introduced. Calibration of the sensing system and experiments with our biped wall-climbing robot W-Climbot is conducted. The results have verified the feasibility, effectiveness and applicability of the proposed sensing system, theoretical analysis and the algorithm for autonomous pose detection and alignment of the suction modules.

Infrared detection of water ingress in a composite laminate crevice based on room temperature evaporation

A novel approach to detect water ingress along rivets and screws or other discontinuities is demonstrated. The approach is implemented through the generation of local vacuum. Vacuum triggers evaporation of water at room temperature. The evaporation process consumes heat energy from the surroundings, causing decrease in local temperature that can be detected using thermography. Using water droplets of different size it is shown that the measured result is a complex phenomenon that includes: (i) actual water cooling due to evaporation, (ii) heat transfer from the substrate; (iii) dynamically changing evaporation rate; (iv) finite IR absorption length of water. In application to the discontinuities, the method unambiguously allows distinguishing dry screws from screws experiencing water ingress. In the case of the wet screw, water volumes below 10μL were sufficient to cause a temperature drop of more than 10°C and the effect to be lasting for tens of seconds. Such changes are easily detectable by IR sensors or cameras. Although the exact estimation of water ingress volume does not seem to be feasible, the method has proven to be reliable and it is several orders of magnitude more sensitive in comparison with results reported in earlier reports.

Design of a dual species atom interferometer for space

Atom interferometers have a multitude of proposed applications in space including precise measurements of the Earth's gravitational field, in navigation & ranging, and in fundamental physics such as tests of the weak equivalence principle (WEP) and gravitational wave detection. While atom interferometers are realized routinely in ground-based laboratories, current efforts aim at the development of a space compatible design optimized with respect to dimensions, weight, power consumption, mechanical robustness and radiation hardness. In this paper, we present a design of a high-sensitivity differential dual species $^{85}$Rb/$^{87}$Rb atom interferometer for space, including physics package, laser system, electronics and software. The physics package comprises the atom source consisting of dispensers and a 2D magneto-optical trap (MOT), the science chamber with a 3D-MOT, a magnetic trap based on an atom chip and an optical dipole trap (ODT) used for Bose-Einstein condensate (BEC) creation and interferometry, the detection unit, the vacuum system for $10^{-11}$ mbar ultra-high vacuum generation, and the high-suppression factor magnetic shielding as well as the thermal control system. The laser system is based on a hybrid approach using fiber-based telecom components and high-power laser diode technology and includes all laser sources for 2D-MOT, 3D-MOT, ODT, interferometry and detection. Manipulation and switching of the laser beams is carried out on an optical bench using Zerodur bonding technology. The instrument consists of 9 units with an overall mass of 221 kg, an average power consumption of 608 W (819 W peak), and a volume of 470 liters which would well fit on a satellite to be launched with a Soyuz rocket, as system studies have shown.

Selection of Appropriate Equipment for Designing Effective Vacuum System

Vacuum systems are designed for a variety of research activities and industrial performs for different vacuum ranges depending upon the process prerequisite. It is very essential that these systems should be designed by selecting the vacuum equipment for proper vacuum generation, precise vacuum measurement and particular vacuum control for immense contribution to the process effectiveness, operational ease, working efficiency and quality product. In this paper effort has been made to clarify the physical concepts to use variety of vacuum pumps, gauges and valves to design different vacuum systems with diverse vacuum ranges for their up to mark effectiveness.

Studies Regarding Pneumatic Equipment for Sowing Small Seeds in Cups

Abstract The paper presents theoretical studies and laboratory experiments regarding pneumatic equipment for sowing small seeds in cups, highlighting the advantages of this type of equipment with superior parameters obtained from the considered crops. Equipment can be used in narrower spaces, being easily to handle and use, of driving the vacuum generator can be done electrically or thermically. By using this equipment, the productivity is increased, the space of establishing the seedlings is reduced, and the seeds norm is diminished. The germinating, rising and development space of plants is assured, equipment can be automated and built by minimum costs. Studies and experimental tests relating to the production index, consumption standard, the emerging degree and the plants percentage obtained will be continued.

Integration of a MEMS-type vacuum pump with a MEMS-type Pirani pressure gauge

The paper concerns the problems associated with the generation and measurement of vacuum in small-volume microelectromechanical (MEMS) devices. A concept of equipping vacuum MEMS with miniature vacuum pump and gauge has been presented. The ion-sorption vacuum micropump developed by the authors has been integrated with two “external” miniature pressure sensors: a specially developed miniature Bayard-Alpert gauge and a MEMS-type Pirani sensor. The pressure during the pumping process was in-situ measured and co-work of vacuum micropump and sensors has been investigated. The experimental results confirmed good pumping properties of the micropump, but indicated that the work of micropump significantly affects the operation of vacuum sensors and vice versa.

The Application of Vacuum Power for Drill Automatic Welding Device

In this paper, a vacuum suction cup robot is introduced, which is used in drill bolt welding machine to add silver brazing sheets. This paper briefly discusses the application of vacuum power on the device. Then through the selection of the degree of vacuum and a vacuum generator, the selection and calculation of the chuck size specify the design process of the vacuum power system. Finally, through the working process of the manipulator and the structural design of the silver brazing box briefly introduce the movement of the vacuum suction manipulator.

Analysis of Flow Rates in the Design of Effector for Unilateral Gripping with Active Vacuum Suction Cup

This article deals with the problems of the need for the required volume and flow rate in the circuit with underpressure in the design of the gripping effector with active suction cups. It presents a process of designing a vacuum generator which is required to power such effector so that it guarantees a quick and secure fixation of handling objects (OM) at handling it with a robot. The article displays a means of determining of so-called evacuationtimes in the process of gripping of OM during the handling tasks.

Preprogrammed, rate-switchable osmotic pumping on a chip

We have successfully demonstrated a passive microfluidic chip that can perform preprogrammed, rate-switchable osmotic pumping in a controlled manner. A polydimethylsiloxane diaphragm powered by osmosis is employed to provide the desired volumetric displacement for microfluidic pumping. Regulated by integrated time switches, the diaphragm is actuated intermittently to realize time-varying pumping patterns. Meanwhile, vacuum generators with dedicated check valves and breather valves are employed to achieve the priming of liquid samples. This preprogrammed microfluidic chip is composed of functional polymers and microfabricated by milling, laser machining, molding and multilayer bonding processes. In the prototype demonstration, vapor-permeable thermoplastic polyurethane is used as the semi-permeable material for osmosis. With an effective permeating area of 10.6 mm2 and a thickness of 15 μm, a constant osmotic pumping rate of 9.3 nl/s is measured. It is demonstrated that the passive micro-chip can be preprogrammed to realize operating sequences of constant-rate pumping alternated with pauses for minutes. The actual pumping rates and on/off periods are found to be less than 5 % different from preprogrammed, while can be readily tailored to achieve desired time-varying transport patterns. As such, timed reaction and incubation sequences can be realized on this passive micro-chip, which could fulfill the needs of a variety of portable and point-of-care testing applications.

Vacuum generation by hydrogen permeation to atmosphere through austenitic and nickel-base-alloy vessel walls at temperatures from 573 K to 773 K

Abstract The permeation of hydrogen through metals is of great concern in hydrogen containment systems. In this study, hydrogen contained in seamless coiled tube vessels made of SUS 316L and Inconel 625 permeated the vessel walls at temperatures from 573 K to 773 K, and the decreasing interior pressure of the vessels was monitored for an extended period to characterize the behavior of the pressure change. It was found that the pressure became lower than the surrounding atmospheric pressure, and the vessels reached a vacuum. Hydrogen permeabilities through SUS 316L and Inconel 625 were determined from the pressure drop measurements. In order to ensure the reliability of the measurements, the permeabilities were also determined with a gas chromatograph that measured the concentration of hydrogen completely permeating the vessel wall. The permeabilities obtained with the two methods were in good agreement with each other. The pressure drop behavior was compared to, and found to be consistent with, theoretical calculations performed using the obtained permeabilities based on Fick’s law of diffusion.

Vacuum oxygen decarburization (VOD) of stainless steel

AbstractHigh costs for vacuum generation and maintenance can be overcome by replacing steam ejector pumps with mechanical vacuum pumps, initially for the vacuum degassing (VD) process but later also for the vacuum oxygen decarburization (VOD) process. Initial concerns about the technical suitability of mechanical pumps for vacuum processing of large heat weights have proven unfounded. There is no real technical upper limit. With detailed knowledge about the vacuum process mechanical vacuum pumps can be successfully engineered for any heat weight where a steam ejector pump would previously have been selected. In fact, suction speed of mechanical vacuum pumps can be ideally controlled to fit the various phases of vacuum processing. This article will show how mechanical vacuum pumps contribute to significant cost reduction and to the possibility of automation of decarburisation, thereby achieving better process control.

Abietane, Labdane, and Pimarane Diterpenoids from the Pulp of Torreya nucifera

Torreya nucifera is an evergreen coniferous tree, widely distributed in Japan, Korea, and People's Republic of China. Its seeds exhibit significant insecticidal activity. The fruits of this evergreen are widely used in folk medicine for the treatment of tapeworm infestation in Korea and to induce abortion in Japan, but most chemical studies of T. nucifera have focused on its leaves and wood. A number of sesquiterpenoids, labdane and abietane diterpenoids, ligans, and flavonoids were identified as active secondary metabolites [1–8]. T. nucifera is a Taxaceae plant endemic to Korea, Japan, and China. In order to compare its constituents with those of Taxus spp. and to understand their taxonomic relationship, we investigated the chemical composition of Torreya nucifera. Five diterpenoids were isolated for the first time from the pulp of the title plant, including one labdane diterpenoid, two abietane diterpenoids, and two pimarane-type diterpenoids. Their structures were established on the basis of 1D and 2D NMR spectrascopic analysis. We report herein the isolation and structure characterization of these diterpenoids and detailed the 1H and 13C NMR data of compounds 1–5. Melting points were measured with an MRK micro-melting point apparatus and were uncorrected. Column chromatographic separations were carried out using silica gel (300–400 mesh, Qingdao Haiyang Chemical Group Corporation, Qingdao, P. R. China). Na2SO4 was the drying agent used in all workup procedures. Solvents and reagents of analytic grade (reagent grade used without further purification) were purchased from commercial sources. TLC was performed on precoated silica gel F254 glass-backed plates without activation. Fractions were monitored by TLC with visualization under UV light (254 and 365 nm) and by dipping the plates into a solution of 10% (v/v) H2SO4 in EtOH followed by heating on a hot plate for 5 min. Analytical HPLC was performed on a Waters 2695 separation module coupled to a 2996 photodiode array detector. Preparative HPLC was carried out on a Waters Delta Prep 3000 instrument coupled to a UV 2487 dual absorbance detector. Analytical HPLC was performed using two Whatman partisil 10 ODS-2 analytical columns (4.6 250 mm) in series. Preparative HPLC was performed using a partisil 10 ODS-2 MAG-20 preparative column (9.4 250 mm). The products were eluted with a 50 min linear gradient of acetonitrile (25 to 100%) in water at a flow rate of 3 mL/min (preparative HPLC). Positive ion fast atom bombardment mass spectra (FAB-MS) was obtained with a Vacuum Generators ZAB-HS instrument. All NMR spectra were recorded on a Varian Unity INOVA 600 or 500 NMR spectrometer equipped with a 5 mm probe at ambient temperature in CDCl3 solution. The 1H and 13C chemical shifts were referenced relative to TMS residue. Typical one-dimensional (1D) 1H and 13C spectra were acquired under standard condition on a Varian Unity INOVA 500/600 spectrometer operating at 499.861/599.913 and 125.690/150.848 MHz, respectively. 1H and 13C chemical shifts are expressed in the scale as parts per million (ppm).

Efficient generation of vacuum and extreme ultraviolet pulses

We demonstrated efficient vacuum and extreme ultraviolet third harmonic generation driven by intense ultrashort fundamental-wave pulses. As the driving pulses were tightly focused upon an argon gas jet to reach relatively high peak intensities, we achieved vacuum ultraviolet pulse energy of 6.4 μJ at 133 nm and extreme ultraviolet (XUV) pulse energy of 199 nJ at 89 nm, with the corresponding conversion efficiency up to 0.26‰ and 0.008‰, respectively. In addition, the intense 400-nm ultrashort driving pulse was up-converted to a 79-nm XUV pulse with pulse energy of 251 nJ and the harmonic generation efficiency was 0.01‰.

Best Magnetic Condition to Generate Hollow Cathode Glow Plasma in High Vacuum

Based on magnetron hollow cathode discharge, the magnetic condition of glow plasma generation in high vacuum, including both direction and magnitude of the applied magnetic field, is theoretically derived and experimentally evaluated in this paper. Single particle orbital theory is introduced to discuss the possibilities to generate glow plasma at gas pressure under 10−2 Pa when the magnetic field direction is parallel or perpendicular or oblique to the electric field direction. A quantitative estimation criterion of magnetic induction intensity is also proposed in theory. The comparison with experiments suggests that glow plasma in high vacuum will form more easily in oblique magnetic field condition and that the criterion is accurate enough to estimate magnetic induction intensity at a certain gas pressure.

Vacuum Large Current Parallel Transfer Numerical Analysis

The stable operation and reliable breaking of large generator current are a difficult problem in power system. It can be solved successfully by the parallel interrupters and proper timing sequence with phase-control technology, in which the strategy of breaker’s control is decided by the time of both the first-opening phase and second-opening phase. The precise transfer current’s model can provide the proper timing sequence to break the generator circuit breaker. By analysis of the transfer current’s experiments and data, the real vacuum arc resistance and precise correctional model in the large transfer current’s process are obtained in this paper. The transfer time calculated by the correctional model of transfer current is very close to the actual transfer time. It can provide guidance for planning proper timing sequence and breaking the vacuum generator circuit breaker with the parallel interrupters.

Compensation of anisotropy effects in a nonlinear crystal for squeezed vacuum generation

Squeezed vacuum can be obtained by an optical parametric amplifier (OPA) with the quantum vacuum state at the input. We are interested in a degenerate type-I OPA based on parametric down-conversion (PDC) where, due to phase matching requirements, an extraordinary polarized pump must impinge onto a birefringent crystal with a large χ(2) nonlinearity. As a consequence of the optical anisotropy of the medium, the spatial spectrum of the generated radiation is affected by the transverse walk-off. In this work we describe a method that reduces the spatial distortions, by using two consecutive crystals instead of one. We show that after anisotropy compensation the two-photon amplitude becomes symmetric, allowing for a simple Schmidt expansion, a procedure that in practice requires states that come from experimental systems free of anisotropy effects. Qualitative experimental observations are made for the case of high-gain PDC.

Start-up operations of MED desalination plants

This paper is related to the previous work (Manenti et al., “Parametric Simulation and Economic Assessment of Heat Integrated Geothermal Desalination Plant”, Desalination, 317, 193–205, 2013) and extends the steady-state simulation and process layout optimization by investigating the procedure to start up multi-effect distillation (MED) desalination plants. The operations involved in the startup procedure, such as seawater supply, energy supply and vacuum generation along the process are considered together with the status of controls to prevent any possible overlapping of these relevant aspects. Segregation of the operations is demonstrated to be essential to prevent any redundancy in the oscillatory behavior of process units that can easily lead to dangerous instabilities of the plant. Moreover, whenever geothermal sources are used for sustainable production of desalinated water, it is fundamental to account for some peculiarities such as certain limitations in controllability and operability of the geothermal source. General guidelines to start up desalination processes are provided; special attention is given to geothermal-supplied plants.

Generation of a continuous-wave squeezed vacuum state at 1.3 μm by employing a home-made all-solid-state laser as pump source

We present a continuous-wave squeezed vacuum generation system at a telecommunication wavelength of 1.3 μm. By employing a home-made single-frequency Nd:YVO4 laser with dual wavelength outputs as the pump source, via an optical parameter oscillator based on periodically poled KTP, a squeezed vacuum of 6.1 dB±0.1 dB below the shot noise limit at 1342 nm is experimentally measured. This system could be utilized for demonstrating practical quantum information networks.

An Interstitial Fluid Transdermal Extraction Chip with Vacuum Generator and Volume Sensor for Continuous Glucose Monitoring

A five layer microfluidic chip which is designed and fabricated for interstitial fluid (ISF) transdermal extraction, collection, and measurement toward the application of continuous and real-time glucose monitoring is presented in this paper. The microfluidic chip consists of a Venturi tube generating vacuum for ISF extraction and fluid manipulation, a novel volume sensor of electrolytic fluid for normal saline input volume control and ISF volume measurement, pneumatic valves for fluid management, and access ports for glucose sensor integration. The output vacuum of the Venturi tube is tested, and a less than 88kPa vacuum has been achieved, when 220kPa external pressure is applied. The feasibility of using the volume sensor to control and measure the normal saline input volume is confirmed by high accuracy and low coefficient of variation (CV=0.0040, n=12). The microfluidic chip is ready for glucose sensor integration in continuous glucose monitoring.

Scanning Transmission Electron Microscopy Analysis of Diesel Soot Particles for Source Attribution

Scanning transmission electron microscopy (STEM) coupled with energy dispersive x-ray analysis (EDX) has been used to characterize the elemental composition of diesel soot samples. The STEM employed in this investigation is the Vacuum Generators Microscope HB603, with a microanalytical resolution approaching 1 nm, allowing the analysis of individual soot particles and aggregates. Quantification of the EDX spectra is accomplished after background and absorption corrections. This information can then be used to pinpoint the fuels and combustion process from which the soot originated. Six diesel soots were analyzed in this study including three from a U.S. Bureau of Mines diesel test engine, two from a West Virginia University diesel test engine, and one from an Orion diesel bus engine. This research showed that soot impurities were found throughout the aggregates, and that only one or two soot particles were necessary to obtain a chemical fingerprint. Some of these elements may be traced to the fuel and lubricant. Other elements were components of the engine itself that combined with the soot particulates during the combustion process. The concept of using a ‘Truth Table’ for the purpose of source attribution is also introduced.