An experimental and numerical study has been performed on a 4-inch globe control valve with the objective of diagnosing local flow behavior and quantifying the different flow parameters to the total ...valve performance. A computer-based data acquisition system, coupled with pressure transducers, were used to obtain experimental measurements of both the upstream and downstream pressures to calculate pressure drop across the valve. The acquired data was used to validate the results of numerical simulations. Four models of single stage multi-hole trims with different hole sizes were numerically studied. The pressure-drop and hence flow coefficient (Cv) of individual holes were quantified. Flow coefficient (Cv) is defined as defined as the volume of water in gallons per minute (GPM) at 60°F that will flow through a fully open valve with a pressure differential of 1 psi across the valve. The flow behavior around the trim was obtained, and these provided valuable insight into the mechanisms that determine the performance of a multi-hole trim. These were used to establish the relationship between the flow coefficient of the valve with passageways in the cage. The focus of the study was directed towards the development and optimization of a single stage multi-hole trim for a globe control valve. Relationships between parameters such as trim hole diameter, hole height (row position) and hole angular position were examined extensively. The results were used to develop a series of analytical expressions to represent the effect of each geometrical feature and predict local Cv. It is envisaged that proposed expressions will feed into current design methodologies for control valve multi-hole trims which offers the prospect of improved overall performance. The final part of the study was to optimise the control valve through a least cost method where the valve selection is based on total cost as a function of valve diameter. A case study example is discussed to show the control valve life cycle cost which has been incorporated in the optimised design.
This article presents the structure and functioning of two pneumatic linear incremental positioning systems and the experimental models designed and built, in order to determine their performances.
Solenoid valve is an important part of smart toilet, which plays a very important role in smart toilet products. The influence of comprehensive performance for solenoid valve on the quality of smart ...toilet is detailed analyzed, the structure of new solenoid valve is designed, comprehensive performance testing system of the solenoid valve is developed, and comprehensive performance for new solenoid valve is tested by using testing system. The test results prove that the new solenoid valve has good comprehensive performance; meanwhile, it also verifies the generality and reliability of comprehensive performance testing system of the solenoid valve.
The usefulness and versatility of a robotic end-effector depends on the diversity of
grasps it can accomplish and also on the complexity of the control methods required to
achieve them. We believe ...that soft hands are able to provide diverse and robust grasping
with low control complexity. They possess many mechanical degrees of freedom and are able
to implement complex deformations. At the same time, due to the inherent compliance of
soft materials, only very few of these mechanical degrees have to be controlled
explicitly. Soft hands therefore may combine the best of both worlds. In this paper, we
present RBO Hand 2, a highly compliant, underactuated, robust, and dexterous
anthropomorphic hand. The hand is inexpensive to manufacture and the morphology can easily
be adapted to specific applications. To enable efficient hand design, we derive and
evaluate computational models for the mechanical properties of the hand’s basic building
blocks, called PneuFlex actuators. The versatility of RBO Hand 2 is evaluated by
implementing the comprehensive Feix taxonomy of human grasps. The manipulator’s
capabilities and limits are demonstrated using the Kapandji test and grasping experiments
with a variety of objects of varying weight. Furthermore, we demonstrate that the
effective dimensionality of grasp postures exceeds the dimensionality of the actuation
signals, illustrating that complex grasping behavior can be achieved with relatively
simple control.
ABSTRACT
The literature on continuous exposition is characterised by two features: (1) concentration on the music of Haydn and (2) the examination of fast movements. This essay deviates from these ...starting points by examining Mozart's slow movements. The aim is to give close readings of a small number of works taken from a limited corpus rather than to provide an overview of Mozart's slow continuous expositions. The works concerned are the slow movements of three‐ and four‐movement chamber‐music works composed after 1775. Of the 42 slow movements in this corpus there are three with a continuous exposition: Larghetto from the Quintet for Piano and Winds, K. 452 (1784), Larghetto from the Quintet for Clarinet and Strings, K. 581 (1789), and Adagio from the String Quintet, K. 593 (1790). These expositions are analysed, and each of them is paired with another exposition from Mozart's slow chamber‐music works that features elements leading in K. 452, K. 581 and K. 593 to continuous organisation. The similarities notwithstanding, these expositions are interpreted as two‐part.
The porous carbons derived from bio-mass precursors for energy storage devices have gained increased research attention due to their cost effectiveness, easiness in fabrication, eco-friendly nature ...and sustainability. In the present work, we have successfully prepared the highly porous carbon with tube-like structures from tea-waste raw material using facile and clean treatments of pre-carbonization, acid washing and KOH activation procedures. The contained inert inorganic impurities were completely removed by acid and KOH treatments, resulting in much increased carbon porosity. The prepared biomass porous carbon has a high pore volume with a large surface area of 1,610 m2 g−1. The electrochemical properties of the prepared porous carbon were analyzed with a 3-electrode configuration in 6 M KOH electrolyte. It is displayed that the porous carbon exhibited the high specific capacitances of 332 F g−1 at 1 A g−1, and 222 F g−1 at 100 A g−1 when current density increased 100 times, representing an outstanding rate performance. Besides, the porous carbon has achieved an excellent long-cycling life with only 2.2% loss of its initial capacitance over 100,000 cycles even at 100 A g−1. The observed desirable electrochemical behavior of the new biomass porous carbon derived from tea waste would be a competitive candidate as cathode material in the development of high-performance and green supercapacitors for advanced energy storage devices.
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•The rod-like biomass porous carbon was prepared from cost-less natural tea waste.•The porous carbon shows hierarchical pores with high surface area of 1610 m2 g−1.•The porous carbon delivers a superb specific capacitance of 332 F g−1 at 1 A g−1.•The carbon loss only 2.2% of capacitance over 100,000 cycles at 100 A g−1.
Single Fe atoms dispersed on hierarchically structured porous carbon (SA‐Fe‐HPC) frameworks are prepared by pyrolysis of unsubstituted phthalocyanine/iron phthalocyanine complexes confined within ...micropores of the porous carbon support. The single‐atom Fe catalysts have a well‐defined atomic dispersion of Fe atoms coordinated by N ligands on the 3D hierarchically porous carbon support. These SA‐Fe‐HPC catalysts are comparable to the commercial Pt/C electrode even in acidic electrolytes for oxygen reduction reaction (ORR) in terms of the ORR activity (E1/2=0.81 V), but have better long‐term electrochemical stability (7 mV negative shift after 3000 potential cycles) and fuel selectivity. In alkaline media, the SA‐Fe‐HPC catalysts outperform the commercial Pt/C electrode in ORR activity (E1/2=0.89 V), fuel selectivity, and long‐term stability (1 mV negative shift after 3000 potential cycles). Thus, these nSA‐Fe‐HPCs are promising non‐platinum‐group metal ORR catalysts for fuel‐cell technologies.
Stay single: Single‐atom catalysts with Fe atoms dispersed on hierarchical porous carbons were prepared by pyrolysis of iron phthalocyanine and unsubstituted phthalocyanine complexes confined within micropores of the porous carbon supports. The resulting catalysts outperformed the commercial Pt/C electrode in alkaline electrolytes and showed an electrocatalytic activity comparable to the commercial Pt/C electrode in acidic media with a better long‐term stability.
Multigait soft robot Shepherd, Robert F; Ilievski, Filip; Choi, Wonjae ...
Proceedings of the National Academy of Sciences,
12/2011, Volume:
108, Issue:
51
Journal Article
Peer reviewed
Open access
This manuscript describes a unique class of locomotive robot: A soft robot, composed exclusively of soft materials (elastomeric polymers), which is inspired by animals (e.g., squid, starfish, worms) ...that do not have hard internal skeletons. Soft lithography was used to fabricate a pneumatically actuated robot capable of sophisticated locomotion (e.g., fluid movement of limbs and multiple gaits). This robot is quadrupedal; it uses no sensors, only five actuators, and a simple pneumatic valving system that operates at low pressures (< 10 psi). A combination of crawling and undulation gaits allowed this robot to navigate a difficult obstacle. This demonstration illustrates an advantage of soft robotics: They are systems in which simple types of actuation produce complex motion.
In this work, we evaluate the capabilities of a new commercially available inductively coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) instrument, the icp TOF (TOFWERK AG, Thun, ...Switzerland), for analysis of liquid samples with a standard pneumatic nebulizer – cyclonic spray chamber sample-introduction system and a microdroplet sample-introduction system. The ICP-TOFMS instrument provides simultaneous, high-speed detection across almost the entire elemental mass range, from around 7–275 amu. The instrument provides a standard mass resolving power ( R m ) of ∼2500 and can provide R m greater than 4000 through the use of collisional cooling prior to the TOF mass analyzer. In standard operation mode (without collision gas), a sensitivity of 60 000 cps ppb −1 is routinely achieved for heavy elements such as U, with two orders of magnitude decrease in sensitivity from high-to-low masses. Limits of detection (LODs) are in the low parts-per-trillion to high parts-per-quadrillion. The data acquisition system of the TOFMS instrument provides a linear dynamic range greater than 10 6 . The native abundance sensitivity of the ICP-TOFMS is 6.5 × 10 −4 on an adjacent mass and is characterized by a non-linear sloping baseline beyond the adjacent mass channel. To obtain simultaneous high-dynamic-range detection, post-acquisition peak fitting and baseline subtraction can be used to reduce the effect of peak tailing on adjacent masses. Simultaneous quantification of adjacent isotopes across six orders of magnitude of signal intensity is possible after baseline subtraction. Advantages of ICP-TOFMS are apparent for high-speed transient analysis. Here, we assess the performance of the icp TOF for the multi-elemental analysis of single microdroplets, with specific emphasis on the characteristics of this approach for 100% transport of liquid samples and for the analysis of nanoparticles. Absolute limits of detection are in the attogram range for single droplets and concentration LODs for the detection of ensembles of droplets are competitive with those attained with pneumatic nebulization sample introduction.
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