Shape Control Method Research Articles

Physical simulation of construction and control of two butted-well horizontal cavern energy storage using large molded rock salt specimens

Underground salt caverns are used globally for large-scale energy storage. In the thinly bedded rock salt in China, two butted-well horizontal (TWH) caverns, as alternatives for energy storage, are regarded as having better suitability and economy than vertical caverns. However, understandings of the cavern shape development and control methods of TWH-caverns remain insufficient. To overcome these shortcomings with respect to TWH-caverns, we conducted physical simulations of TWH-cavern construction using a high strength steel mold and molded large rock salt specimens. We established a platform for physical simulation of TWH-cavern water-solution construction using the large molded rock salt specimens, so that the construction process is visible and easily observed. Six groups of physical simulations of TWH-cavern construction were designed and implemented. The variables which affect the cavern outline expansion were investigated and compared, including water injection rate, transferring of injection well, oil blanket, and retreating position of the water outlet. Finally the expansion rules of the cavern outline, and different effects when injecting from an inclined well vs. From a vertical well were explored, as well as an attempt of retreating water outlet. This study provides significant guidance for constructing horizontal caverns for energy storage in thinly bedded rock salt.

An optimized non-linear input shaper for payload oscillation suppression of crane point-to-point maneuvers

Payload oscillation suppression in point-to-point maneuvers is a challenging problem in the design and control process of overhead crane systems. To address this issue, this article proposes an input shaping control method coupled with a genetic algorithm strategy to tune the jib input acceleration. A polynomial function is defined as the input for the jib acceleration to move the payload on a specific track that satisfies the system constraints, while the desired final conditions are achieved. All three phases of a crane maneuver, including filling the ladle, moving the payload to a new position, and eventually unloading the ladle, are captured by the optimization algorithm. The proposed method is evaluated for both constant and variable hoisting cable length cases. The numerical results indicate that the introduced method enables the crane to safely perform an accurate controlled maneuver by constraining the payload angular motion within a certain range, which is critical in handling sensitive loads. In compared with the existing techniques, the new input shaper also provides a faster system response owing to the fact that it is driven by a continuous input function. A sensitivity study is performed and a non-sensitive optimized input polynomial function is obtained for the variable hoisting length case.

Spontaneous shape and phase control of colloidal ZnSe nanocrystals by tailoring Se precursor reactivity

A novel synthetic method of shape and phase control of ZnSe nanocrystals by tailoring Se precursor reactivity is reported.

Non-spherical polymersomes: formation and characterization.

Polymersomes are self-assembled hollow membrane sacs that are not only able to encapsulate hydrophobic and/or hydrophilic molecules, but also possess exceptional chemical and physical stability, structural versatility, and surface modifiability. For the above reasons, polymersomes have in recent years emerged as a powerful tool for a wide range of applications in the fields of biomimicry and drug delivery. The full potential of polymersomes, however, has yet to be harnessed due to a lack of appreciation of existing shape control methods. This very much contrasts the field of inorganic nanoparticle synthesis where non-spherical hollow metal nanoparticles are routinely prepared and used. Here, we summarize recent efforts over the past decade to study the morphological transformation of conventionally spherical polymersomes into non-spherical polymersomes.

Research on flexible roll profile electromagnetic control technology in precision rolling mill

To obtain a better strip shape control method, this paper proposes roll profile electromagnetic control technology (RPECT) based on induction heating technology and the principle of metal thermal expansion. Using the thermally driven and internal constraint mechanism of the electromagnetic stick, the technology innovatively converts the energy of induction heating into a thermodynamic hybrid power source, which achieves segmented micro-scale flexible roll profile adjustment and enhances the capacity for strip shape control. To research the technology, an electromagnetic control roll (ECR) with five control regions is built based on a ϕ560 × 2180 mm roll, and an electromagnetic-thermal-mechanical coupling model is established. Based on the model, the typical roll profile curves obtained by the ECR are researched, the strategy of increasing the growth rate of the roll crown is analysed, and the applications of RPECT in strip shape control and cold rolling are discussed. Finally, a roll profile electromagnetic control experiment platform is established to verify the model accuracy and feasibility of RPECT. The results show that RPECT can realize flexible roll profile adjustment and that the model has sufficiently high computational accuracy to research the roll profile of multi-segment RPECT.

Hierarchical robust switching control method with the Improved Moving Filaments equilibrium reconstruction code in the feedback for tokamak plasma shape

The paper describes a new hierarchical tokamak plasma shape control method implemented in the system with switching robust controllers and matching state vectors. A system robustness was achieved via the H∞ loop-shaping design. A novel modeling approach was used for the feedback system simulation: tokamak plasma equilibrium was calculated by the reconstruction code receiving the sum of experimental scenario signals and the output signals of a linear parameter varying (LPV) model, and sending the output to the multivariable plasma shape controller to close the loop. The LPV plant model is based on plasma equilibria reconstructed from the experimental data of the spherical tokamak Globus-M and is used to simulate plasma responses to small deviations from tokamak discharge scenario. The control system components were designed and combined to achieve high-performance operation during short pulses of plasma with total duration of about 200 ms and the divertor phase time length of 20–25 ms. The non-iterative Improved Moving Filaments method was developed for the plasma equilibrium reconstruction with the simultaneous determination of coordinates and currents of filaments. The plasma shape is controlled via the magnetic field at X-point and poloidal fluxes on a plasma separatrix, without calculation of the gaps between the plasma separatrix and the first wall. The hierarchical feedback control method was used in simulations of the entire plasma discharge with the transition from the limiter to the divertor plasma magnetic configuration. The control system was discretized and simulated on a high-speed computer to be prepared for application in Globus-M experiments by a real time test bed.

Photocatalysis electroless plating of copper pattern on Al2O3 ceramic substrate combined with template shape control method

ABSTRACTA convenient and efficient approach for copper pattern preparation on Al2O3 ceramic substrate has been developed. The anatase nano-TiO2 film was firstly deposited on the surface of Al2O3 ceramic substrate to provide electron-hole pairs in subsequent photocatalysis electroless copper plating (PECP), and then PECP combined with template shape control method was initiated by ultraviolet light to fabricate the desirable conductive pattern. A continuous copper pattern layer could be obtained by controlling the electroless plating process during PECP. A low resistivity of about 3.49 × 10−8 Ω·m of the copper layer was achieved, which was only about 2 times higher than that of pure copper. Moreover, such a copper layer exhibited satisfactory smoothness with roughness of Ra 472 nm and reliable adhesion with bonding strength of higher than 37 MPa to substrate. This approach proposes a potential way to realize selective surface metallization on ceramic substrates without high temperature and any sophisticated equipment.

Adaptive Shape Control for Thermal Deformation of Membrane Mirror with In-plane PVDF Actuators

Optical membrane mirrors are promising key components for future space telescopes. Due to their ultra-thin and high flexible properties, the surfaces of these membrane mirrors are susceptible to temperature variations. Therefore adaptive shape control of the mirror is essential to maintain the surface precision and to ensure its working performance. However, researches on modeling and control of membrane mirrors under thermal loads are sparse in open literatures. A 0.2 m diameter scale model of a polyimide membrane mirror is developed in this study. Three Polyvinylidene fluoride (PVDF) patches are laminated on the non-reflective side of the membrane mirror to serve as in-plane actuators. A new mathematical model of the piezoelectric actuated membrane mirror in multiple fields, (i.e., thermal, mechanical, and electrical field) is established, with which dynamic and static behaviors of the mirror can be analyzed. A closed-loop membrane mirror shape control system is set up and a surface shape control method based on an influence function matrix of the mirror is then investigated. Several experiments including surface displacement tracking and thermal deformation alleviation are performed. The deviations range from 15 μm to 20 μm are eliminated within 0.1 s and the residual deformation is controlled to micron level, which demonstrates the effectiveness of the proposed membrane shape control strategy and shows a satisfactory real-time performance. The proposed research provides a technological support and instruction for shape control of optical membrane mirrors.

Concurrent Design of Linear Control with Input Shaping for a Two-Link Flexible Manipulator Arm

Input shaping is an effective vibration control technique for flexible systems with known dynamic characteristics. However, due to its open-loop nature, it must be combined with a feedback controller to enable rejection of unknown disturbances. Although a number of researchers have demonstrated the effectiveness of combining input shaping and feedback control methods, performance gains can be made by cooperatively designing the feedback gains and input shaping sequence. This paper presents a preliminary investigation of such a control method on a two-link flexible manipulator. This formulation allows for energy-efficient point-to-point motion while simultaneously minimizing command-induced vibration. Simulations demonstrate the effectiveness of this preliminary work.

Hamiltonian methods of modeling and control of AC microgrids with spinning machines and inverters

This paper presents a novel approach to the modeling and control of AC microgrids that contain spinning machines, power electronic inverters and energy storage devices. The inverters in the system can adjust their frequencies and power angles very quickly, so the modeling focuses on establishing a common reference frequency and angle in the microgrid based on the spinning machines. From this dynamic model, nonlinear Hamiltonian surface shaping and power flow control method is applied and shown to stabilize. From this approach the energy flow in the system is used to show the energy storage device requirements and limitations for the system. This paper first describes the model for a single bus AC microgrid with a Hamiltonian control, then extends this model and control to a more general class of multiple bus AC microgrids. Simulation results demonstrate the efficacy of the approach in stabilizing and optimization of the microgrid.

Synthesis of spherical Prussian blue with high surface area using acid etching

Prussian blue (PB, Fe(III)4[Fe(II)(CN)6]3) is a prototype of metal hexacyanoferrates with well-known magnetic properties and electrochromic (redox reaction between Fe2+ and Fe3+) and electrochemical behavior [1,2]. The shape-control of PB has drawn increasing attention owing to its shape-dependent properties such as porosity, storage, and magnetism with stacking order [3]. Wet chemical routes are usually considered a powerful method for top-down shape control by carefully tuning the reaction conditions. However, previous reports focused on chalcogenides, metals, and oxides with selective etching of the special facets of the nanomaterial [3].In this study, we report a hydrothermal synthesis method to control the shape of monodisperse PB from cube to sphere via selective acid etching. Polyvinylpyrrolidone (PVP), used as a surfactant, not only maintains a good dispersion of the particle without aggregation by stabilizing the PB particles during crystallization but also plays a key role in the etching process after mixing with strong acid. The size and shape of the resulting spherical PB particles were sensitive to the molar concentration of acid solution. Consequently, the spherical PB had a high specific surface area and the calcined PB exhibited superparamagnetic properties. The results show that the spherical PB can be utilized in applications such as magnetic-field-guided drug delivery, cell labeling, and contrast agents for magnetic resonance imaging. The chemical and physical properties of the obtained samples were characterized using X-ray diffraction, Brunauer–Emmett–Teller analysis, Raman spectroscopy, and scanning electron microscopy.

Formation of non-spherical polymersomes driven by hydrophobic directional aromatic perylene interactions

Polymersomes, made up of amphiphilic block copolymers, are emerging as a powerful tool in drug delivery and synthetic biology due to their high stability, chemical versatility, and surface modifiability. The full potential of polymersomes, however, has been hindered by a lack of versatile methods for shape control. Here we show that a range of non-spherical polymersome morphologies with anisotropic membranes can be obtained by exploiting hydrophobic directional aromatic interactions between perylene polymer units within the membrane structure. By controlling the extent of solvation/desolvation of the aromatic side chains through changes in solvent quality, we demonstrate facile access to polymersomes that are either ellipsoidal or tubular-shaped. Our results indicate that perylene aromatic interactions have a great potential in the design of non-spherical polymersomes and other structurally complex self-assembled polymer structures.

Block layout for attraction-based enterprises

This paper proposes an approach for block layout for attraction based enterprises such as theme parks, museums, casinos and exhibitions. The approach takes into account the attraction of individual entities within the enterprise and any adjacency requirements among entities while enforcing reasonable shapes. Using Moran's I of spatial statistics and a newly devised shape control method, an optimization mathematical model is established. To solve the model, a space filling curve mechanism works with a tabu search heuristic. The effectiveness and practicality of the approach are demonstrated using three layout cases including the SeaWorld San Diego Park. The approach is easy to use, effective and can readily accommodate varying degrees of preference regarding adjacencies and fixed entities.

(Keynote) Design and Synthesis of Electrocatalysts

Electrocatalyst is the key in developing electrochemical energy conversion and storage, and in green chemistry of electrosynthesis using electrons as reagents. The activity, selectivity and stability of electrocatalysts depend strongly on both their bulk and surface structures. Therefore, the rational design and control-synthesis of electrocatalysts are the central subject, and mainly focused on the structure-catalytic functionality of nanomaterials, since practical electrocatalysts often consist of nanosized particles substrated on conductive support. The bulk structure of nanoparticles could be tuned by changing their chemical nature and composition, while tuning their surface structure is more difficult, especially the high catalytic activity corresponding to high surface energy that leads to disappear thermodynamically the nanoparticles during their growth. We have devoted, in recent years, to the structure design and controlled synthesis of electrocatalysts of metal/alloy nanocrystals of high surface energy, and non-precious metal electrocatalysts as well. (1) Tuning the surface atomic arrangement of well-defined metal nanocatalysts. Well-defined Pt, Pd, Rh and Cu nanocrystals enclosed by high-index facets have been successfully obtained by developing electrochemically shape-controlled synthesis, such as tetrahexahedral nanocrystals (THH NCs) enclosed with {hk0} high-index facets, trapezohedral nanocrystals (TPH NCs) with {hkk} high-index facets, triambic icosahedral nanocrystals (TIH NCs) with {hhl} high-index facets and hexoctahedral Pt NCs (HOH NCs) with {hkl} facets. As the high-index facets contain a high density of active centers, these NCs of high surface energy exhibit much higher electrocatalytic activity than commercial catalysts for small organic fuel oxidation reactions. (2) Tuning the electronic structure of Pt- and Pd-based nanocatalysts. The electronic structure of NCs catalysts has been tuned either by surface decoration using foreign adatoms, or through alloying Pt and Pd with other metals. Different adatoms such as Bi, Ru and Au were used to decorate the THH Pt NCs, and both THH and TPH Pt-based alloy nanocatalysts were prepared by electrochemically shape-controlled method. The THH and TPH alloy NCs preserve the high-index facets while hold a synergy of electronic effect that enhances further the electrocatalytic activity. (3) Synthesis of non-precious metal electrocatalysts with high ORR activity. Fe/N/C is a promising electrocatalyst for oxygen reduction reaction (ORR). By well-screening the precursors, optimizing the synthetic procedures and surface decoration, the resulted Fe/N/C exhibits high activity and stability in both acid and alkaline conditions. The results demonstrated that the Fe/N/C-SCN catalysts in a proton exchange membrane fuel cell (PEMFC) can output a maximum power density of 1.03 W/cm2, and by using 2-aminothiazole as precursor the synthesized S-doped Fe/N/C catalyst with graphene nanosheets can yield a peak power density of 164 mW/cm2 in an anion exchange membrane fuel cell (AEMFC).Acknowledgements. The studies were supported by NSFC (21621091, 21573183) REFERENCES: [1] Tian, N. ; et al. Science 2007, 316, 732. [2] Tian, N.; et al. J. Am. Chem. Soc. 2010, 132, 7580.[3] Zhou, Z.-Y. ; et al. Angew. Chem. Int. Ed. 2010, 49, 411.[4] Zhou, Z.-Y. ; et al. Chem. Soc. Rev. 2011, 40, 4167. [5] Li, Y.-Y. ; et al. Chem. Commun. 2012, 48, 9531. [6] Wei, L. ; et al. Chem. Commun. 2013, 49, 11152. [7] Tian, N.; et al. Faraday Discuss. 2013, 162, 77.[8] Xiao, J.; et al. J. Am. Chem. Soc. 2013, 135, 18754.[9] Yu N.-F. ; et al. Angew. Chem. Int. Ed. 2014, 53, 5097.[10] Qu, X. M.; et al. Electrochim. Acta 2015, 182, 1078. [11] Liu, D. Y.; et al. J. Am. Chem. Soc. 2015, 137, 9772. [12] Wang, Y. C.; et al. Angew Chem Int Ed. 2015, 54, 9907.[13] Chen, C.; et al. Chem. Commun. 2015, 51, 17092.5[14] Zhang, B.-W.; et al. Nano Energy 2016, 19: 198. [15] Qu X.-M., et al. Chem. Comm. 2016, 52: 4493. [16] Zhang, B.-W.; et al. ACS Catal. 2017, 7, 892.[17] Wang, Y. C.; et al. ACS Energy Lett. 2017, 2, 645. [18] Zhang Z-C., et al. Nano Energy DOI: 10.1016/j.nanoen.2017.02.023

Shape Control of a Snake Robot With Joint Limit and Self-Collision Avoidance

This paper proposes a shape control method for a snake robot, which maintains head position and orientation, and avoids joint limits and self-collision. We used a passive wheeled snake robot that can switch the grounded/lifted status of its wheels. We derived a kinematic model of the robot that represents its redundancy as both joint angles [the shape controllable points (SCPs)] and the null space of the control input. In the control method, the shape is changed by sequential control of the SCPs, and the null space of the control input is used for joint limit and self-collision avoidance. Jumps in control input do not occur, although the controlled variable and the model are switched. Simulations and an experiment were used to demonstrate the effectiveness of the proposed method.

Shape-controlled fabrication of nanopatterned samarium-doped cerium oxide thin films using ultraviolet nanoimprint lithography

A shape-controlled method for the nanoscale patterning of cerium oxide thin films was demonstrated in this work. An ultraviolet-curable precursor-containing resin was newly developed for samarium-doped and undoped cerium oxide films, and ultraviolet nanoimprint lithography was employed for the nanopatterning. Various nanostructure shapes such as lines, circular pillars, and circular holes were fabricated, and a minimum feature width of 45nm was realized by patterning and subsequently shrinking the structures. The fabricated film was confirmed to be cerium dioxide, both undoped and doped with Sm. The effects of the annealing temperature on the crystallinity of the nanostructure and the controllability of the doping ratio were investigated. We believe that this work will provide a new path for preparing nanostructured cerium oxide for energy applications and a basic platform for analyzing the relationship between the structure and performance of size-controlled nanostructures.

Controllable synthesis of SnS2 nanostructures with high adsorption and photocatalytic activities

Series of SnS2 nanostructures were synthesized by a facile refluxing process. Influencing factors on the microstructures and properties of SnS2 were investigated, including the reaction temperature, adding sequence of reagent and the solvent. The results indicated the as-prepared SnS2 products in lower temperature had larger surface areas and superior adsorption capability than that in higher temperature. SnS2 nanoflowers prepared at 120°C in ethylene glycol exhibited remarkable adsorption capability for cationic dyes and heavy metal of Pb2+, Cd2+. Intriguingly, the products also showed prominent visible light photocatalystic activity for Methyl Orange (MO). The formation mechanisms of different SnS2 nanostructures were proposed; the release of S2- played a crucial role on controlling the morphology of SnS2. The simple shape-controlled method can be extended to the synthesis of other metal sulfides and the high adsorption property is favorable to it coupling with other semiconductors or noble metals to far improve photocatalytic activity.

Discharge current shape control method and experiment in wire EDM

In order to study the effect of discharge current shape on surface roughness and processing speed in wire EDM process, a pulse power generator of adjustable current shape was developed. Based on half-bridge topology of pulse power generator, the various current shapes were generated by the control method of single-arm intermittent turn-on power tubes, regulating the gap discharge current raising time and falling time. The comparison experiment between rectangular waveform and triangular waveform indicated that the processing speed of rectangular waveform was high and the surface roughness of triangular waveform was good. To avoid the contradiction between the processing speed and surface roughness, the narrow triangular pulse combination waveform was investigated. According to the rectangular waveform and triangular waveform machining features, a multiple cutting strategy was discussed that rectangular waveform was used to rough cutting and the triangular waveform was used to trim cutting. The experiment shows that the cutting strategy can obtain a good processing effect.

Shape Control of Cable-Network Antennas Considering the RF Performance

Manufacturing errors can result in variation of the cable tensions and degradation of the RF performance of cable-network antennas. To compensate the effects of the manufacturing errors, a novel shape control procedure, which takes the RF performance into consideration, is presented. Both the boundary cables and the tension ties are selected as adjustable cables. Sensitivity analysis is adopted to evaluate the influence of the unstrained cable lengths on the RF performance and cable tensions. The antenna performance is finally expressed as the incremental form of the adjustable cable lengths on the basis of the sensitivity analysis. A mathematical model of the shape control procedure is established and solved using optimization strategy. The proposed shape control method is applied to a 10-m diameter cable-network antenna. Numerical results show that the directivity of the antenna is more sensitive to the boundary cable lengths, while the tension in a cable is much more sensitive to the length changes of itself, the cables connected to it, and the boundary cables. Comparisons of the directivities and tensions before and after shape control demonstrate the feasibility of the proposed shape control method and recommend the antenna RF performance as the shape control objective.

The Motion Planning of Overhead Crane Based on Suppressing Payload Residual Swing

Since the overhead crane system is subject to under actuation system due to that overhead crane and payload are connected by flexibility wire rope. The payload generates residual swing when the overhead crane is accelerating/ decelerating the motions. This may cause trouble for the payload precise positioning and motion planning. Hence, an optimization input shaping control method is presented to reduce the under actuated overhead crane’s payload swing caused via the inertia force. The dynamic model of the overhead crane is proposed according to the physics structure of the crane. The input shaper based on the motion planning of the crane is used as the feed forward input to suppress payload residual swing. Simulation and experiment results indicate that the ZV input shaper and ZVD input shaper can reduce the payload swing of the overhead crane.