Vacuum Adsorption Research Articles

Surrogate model-based modelling and optimization of the adsorption performance of a vacuum adsorption system under leakage conditions

The leakage phenomenon has become a major challenge in engineering applications for vacuum adsorption technology. To achieve efficient design optimization of the vacuum adsorption system based on the finite element model, an optimization design method based on residual adaptive fitting of the surrogate model is proposed. The surrogate model for the adsorption performance and influencing parameters of the vacuum adsorption system is established under leakage conditions by the response surface method (RSM). The residuals generated by the RSM are fitted using the kriging model and incorporated into the construction of the RSM. The established surrogate models are updated by learning functions, combining genetic algorithms to optimize the parameters of the vacuum adsorption system. The optimization results indicate that appropriate parameter configurations can enhance adsorption performance and reduce energy consumption, and also validate the superiority of the proposed method.

Preparation and characteristics of CuS-CNTs modified PVDF-based flexible composite phase change films

It is indisputable that the impact of buildings on global energy demand. To address the issue of excessive energy consumption in buildings, this manuscript proposes the preparation of a flexible composite phase change films with excellent solar energy absorption conversion and thermal management capabilities. In this paper, composite phase change material was obtained by adsorbing paraffin into expanded graphite (EG) using vacuum adsorption method. The photothermal material copper sulfide‑carbon nanotubes (CuS-CNTs) was synthesized by hydrothermal reaction. The dispersion of EG and carbon nanotubes (CNTs) in polyvinylidene fluoride (PVDF) matrix was enhanced under the influence of polyvinylpyrrolidone (PVP). The flexible and bendable films were finally prepared by using the non-solvent-induced phase separation method. The latent heat of the film reaches 63.63 J/g, and the thermal conductivity of the film system approaches to 0.53 W/(m·K) through the adsorption of the high thermal conductivity enhanced phase EG and the intervention of CNTs. The photothermal conversion ability of CuS-CNTs improves the photothermal performance of the film, and the solar energy utilization reaches 46.2 % under simulated sunlight. The experimental results show that the prepared films can effectively convert solar energy into thermal energy and store it in the form of latent heat, and the films can release the energy in the form of heat again at low temperatures. Utilizing this property, the film can be applied to the field of building materials, which demonstrates great potential and prospect in reducing energy consumption and carbon emission in buildings. The prepared composite phase change film for photothermal conversion provides a new idea for modern building thermal management materials.

Preparation and performance study of modified diatomite based PCM for construction

Phase change energy storage technology provides a good solution to the spatial and temporal mismatch of energy use in buildings, but organic solid–liquid phase change materials suitable for the building sector limit their application due to leakage problems. To mitigate the effects of the above problems, diatomite (DME) is designed as the carrier for encapsulation in this experiment. Adsorption performance of DME is improved through double effects of 600°C high-temperature calcination and hydrochloric acid modification. The binary low eutectic mixture was prepared by co-melting of lauric acid (LA) and octadecyl alcohol (OD) with mass ratio of 70:30. Shape-stabilized composite phase change material (SSCPCM) was prepared by vacuum adsorption method with LA-OD and DME with a mass ratio of 35:65 and the melting temperature and latent heat of SSCPCM are 39.10°C and 54.02 J/g. It was experimentally evaluated that the surface impurities of modified DME under microscopic conditions were removed and LA-OD was uniformly embedded in the micropores of DME, and the prepared SSCPCM was able to maintain a thermal inertia of 39°C with good thermal properties and thermal stability, thus SSCPCM could be used as a building energy-saving material to reduce building energy consumption, in addition to expanding the utilization of inorganic mineral materials.

Flexible loofah sponge-based phase change composite for thermal protection and wearable thermal management

To address the escalating demand for sophisticated thermal management in electronics, energy batteries, and wearable devices, extensive research has been dedicated to developing shape-stabilized and highly thermally conductive phase change composites (PCCs). However, their inherent rigidity and limited flexibility pose significant challenges for practical applications. In response, we have engineered a novel and flexible PCC by integrating loofah sponge (LS) and styrene-isoprene-styrene block copolymer (SIS) as co-supporting framework with paraffin wax (PW) as heat storage medium, further enhanced with carbon nanotubes (CNTs). The process began with the vacuum adsorption of PW into an ammonia-softened LS, which forming a fibrous network. This was followed by the introduction of a mixed melt of SIS and PW, physically cross-linked and dispersed with CNTs, into the LS fibrous network. The composite was then cooled and shaped to produce the (final) PCC. The resultant PCC exhibited remarkable ductility with an elongation of approximately 780 % and a maximum tensile strength of ∼2 MPa. Furthermore, it maintained thermal reliability and dimensional stability over long-term usage, with a melting heat enthalpy as high as 146.4 J/g. This flexible PCC, which combines high latent thermal energy storage, temperature regulation, and thermally induced assembly properties, shows considerable promise for thermal protection and portable thermal management in electronic devices.

Full surface profile measurement of a small sized ball based on a stitching measurement method by reversal clamping

For the full surface profile measurement of a small sized ball, traditional measurement methods inevitably have blind measurement areas since clamping part cannot be directly measured. To address the challenge of measuring the full surface, this paper proposed a reversal clamping measurement method based on a bidirectional vacuum adsorption system. The position of the measuring part and the clamping part was exchanged by reversal clamping the workpiece, and the full surface was obtained by stitching two measurement results before and after reversal clamping process. Two visual sensors were used to monitor the reversal clamping processes, and the error model was established to separate the alignment and scanning errors. Experiments were performed with the measurement system and a ball with diameter of 4 mm, the feasibility of the full surface measurement was verified to be with a measuring accuracy of hundred nanometer-level.

A novel Pumice@PVA membrane with high separation efficiency for oil-water emulsion application

Oil pollution poses a major threat to both human health and economic development, and therefore the development and improvement of oil-water separation technology is urgent. Traditional methods have problems such as complicated preparation, high cost and the vulnerability of lipophilic materials to oil contamination. Therefore, finding an inorganic material that meets the requirements of underwater superoleophobic performance and reduces surface modification has become a new demand. In this study, natural pumice was found for the first time to have excellent underwater superoleophobic performance and chemical stability, and the underwater superoleophobic filter membrane was prepared by vacuum adsorption using hydrogen bond cross-linking between natural pumice and PVA. The experimental data show that the prepared PVA/natural pumice ultrafiltration membrane has superhydrophilic and superoleophobic properties, and exhibits excellent stability (OWA>150°) under the harsh environment of strong acid and strong alkali. In addition, the composite membrane has good emulsion separation efficiency (>97 %) and a separation flux of 39.91 Lm-2h-1. It is demonstrated that the composite membrane has oleophobic and wettable properties, and is capable of separating both oil-water mixtures without phase mixing and oil-in-water emulsions without oil contamination. This study provides a new idea for the preparation of superoleophobic materials for oil-water separation, which has the potential for large-scale application.

Shelf Life of Minced Pork in Vacuum-Adsorbed Carvacrol@Natural Zeolite Nanohybrids and Poly-Lactic Acid/Triethyl Citrate/Carvacrol@Natural Zeolite Self-Healable Active Packaging Films.

Enhancing food preservation and safety using environmentally friendly techniques is urgently needed. The aim of this study was to develop food packaging films using biodegradable poly-L-lactic acid (PLA) as biopolymer and carvacrol (CV) essential oil as an antioxidant/antibacterial agent for the replacement of chemical additives. CV was adsorbed onto natural zeolite (NZ) via a new vacuum adsorption method. The novel nanohybrid CV@NZ with a high CV content contained 61.7%wt. CV. Pure NZ and the CV@NZ nanohybrid were successfully dispersed in a PLA/triethyl citrate (TEC) matrix via a melt extrusion process to obtain PLA/TEC/xCV@NZ and PLA/TEC/xNZ nanocomposite films with 5, 10, and 15%wt CV@NZ or pure NZ content. The optimum resulting film PLA/TEC/10CV@NZ contained 10%wt. CV@NZ and exhibited self-healable properties, 22% higher tensile strength, 40% higher elongation at break, 45% higher water barrier, and 40% higher oxygen barrier than the pure PLA/TEC matrix. This film also had a high CV release content, high CV control release rate as well as 2.15 mg/L half maximal effective concentration (EC50) and 0.27 mm and 0.16 mm inhibition zones against Staphylococcus aureus and Salmonella enterica ssp. enterica serovar Typhimurium, respectively. This film not only succeeded in extending the shelf life of fresh minced pork, as shown by the total viable count measurements in four days but also prevented the lipid oxidation of fresh minced pork and provided higher nutritional values of the minced meat, as revealed by the heme iron content determination. It also had much better and acceptable sensory characteristics than the commercial packaging paper.

Integrated gypsum composite material for energy storage and thermal insulation: Assessment of mechanical performance, thermal properties and environmental impact

The development of gypsum-based construction materials with energy storage and thermal insulation functions is crucial for regulating indoor temperatures, reducing building energy consumption, and mitigating CO2 emissions. In this study, graphene and expanded vermiculite (EV) were used as paraffin carriers to prepare a novel dual-carrier composite energy storage material called P/G-EV, which was developed through ultrasound, a constant-temperature water bath, and vacuum adsorption. In addition, a novel energy storage–thermal insulation integrated–gypsum (ESTIIG) composite material was developed using P/G-EV as the energy storage layer (ESL) and EV as the thermal insulation layer (TIL) compounded with phosphorus building gypsum. The thermal properties, mechanics, apparent density, temperature control performance in a real environment and environmental impact of ESTIIG were evaluated, and the temperature control mechanism was analyzed. The results reveal superior thermal stability and thermal conductivity of the P/G-EV carrier.P/G-EV overcomes the low thermal conductivity and leakage problems associated with paraffin, exhibiting a phase change temperature and latent heat of 21.7 °C and 101 J/g, respectively, during the heat absorption stage. In ESTIIG, P/G-EV and EV are compounded with phosphorus building gypsum to form an ESL and a TIL. The overall mechanical performance of ESTIIG meets the requirements of construction applications. Among the variants of ESTIIG, ESTIIG-1, with an ESL/TIL thickness ratio of 3:1, exhibits the best real-world temperature control performance and environmental benefits, providing a more stable and comfortable indoor temperature. Furthermore, this study provides data and theoretical references for the design of ESTIIG through real-world temperature control monitoring and analysis of the temperature control mechanism.

A novel stereotyped phase change material with a low leakage rate for new energy storage building applications

Phase change materials (PCM) have been widely studied in the field of building energy storage. However, industrial grade high latent heat phase change paraffin (PW) has the problem of high melting point and easy leakage, and at the same time, it is necessary to absorb municipal solid waste on a large scale and reduce the damage of waste cellular concrete (WCC) to the urban ecological environment. Using binary paraffin wax (BP) prepared by hot fusion of solid paraffin (SP) and liquid paraffin (LP) as composite phase change materials, polypropylene (PP) and porous material WCC as support materials, a new WCC/PP/BP stereotyped phase change material (FCPCM) with low leakage rate and good stability was prepared by melt blending method and vacuum adsorption method, to meet the energy storage needs of buildings. The chemical compatibility, thermal performance and morphological stability of the prepared FCPCM were tested, and the heat storage/release performance test experiments were carried out to explore the thermal performance of the prepared energy storage concrete. The results show that the Encapsulated WCC/PP/BP has no new substance and good chemical compatibility. The results of scanning electron microscope (SEM) and mercury injection instrument (MIP) show that WCC has good adsorption properties for PP/BP. The melting phase change temperature increases by 14.08%, the latent heat of phase change decreases by 42.94%, and the initial phase change thermal properties are still maintained after several phases of phase change. It can maintain a stable form at 150℃. The 24 h leakage rate remained below 1%, which was nearly 44% lower than that of FCPCM with PP as the support material. Thermogravimetric curve (TGA) shows that the thermal stability of encapsulated FCPCM increases by 25.59%. In addition, the thermal performance test of energy storage concrete shows that compared with traditional concrete, energy storage concrete has greater heat storage density and stronger temperature control ability, which can effectively realize building energy saving.

A New Manipulating Method of Metal Micro-Components Based on Electrochemistry

This article presents a new manipulating method of metal micro-components based on electrochemistry aiming at the problems of inaccurate release and easy damage to manipulated objects by conventional micro gripping tools and vacuum adsorption tools. This method uses a small-sized micropipette to manipulate large-sized metal micro-components. The reliable picking up is achieved by forming a strong chemical bond between the small-sized pipette and the manipulation object. The accurate and non-destructive release is achieved by converting the chemical bonding force into a more easily overcome capillary force through electrolysis. The electrochemical and the force models of the metal microcomponents based on electrochemistry are simulated by COMSOL and Abaqus, to obtain optimal electrochemical parameters and manipulation strategies. The experiments of picking up and releasing were performed to demonstrate the performance of the proposed method. The results show that this method can enable reliable and accurate manipulation of large-size objects with small-size tools and have a high success rate and efficiency.

Design and therapeutic application of trans‐sodium crocetinate‐loaded cyclodextrin metal–organic frameworks as an enteric preparation for treating chronic heart failure

Chronic heart failure (CHF) arises from structural and functional changes in the myocardial tissue attributable to various etiologies. Crocetin and its derivative trans‐sodium crocetinate (TSC) have exhibited cardioprotective attributes; however, their poor aqueous solubility and bioavailability impede clinical development. This study aimed to construct a cyclodextrin metal–organic frameworks (CDMOFs)‐based oral delivery system to enhance the pharmacokinetic profile and therapeutic efficacy of TSC for CHF treatment. TSC was loaded into the synthesized γ‐CDMOFs via vacuum adsorption. The CDMOFs@TSC formulation was characterized and evaluated in vitro. Pharmacokinetic and pharmacodynamic analyses were performed in beagle dogs and CHF rats induced by coronary artery ligation, respectively. Both TSC and CDMOFs@TSC elicited no discernible toxicity or pathological changes in major organs of rats, providing preliminary evidence for their biosafety. Pharmacokinetic study in beagle dogs demonstrated that CDMOFs@TSC capsules markedly increase the relative oral bioavailability by 198% versus free TSC capsules. In rats afflicted with CHF, the administration of CDMOFs@TSC yielded notable enhancements in cardiac function. Additionally, it precipitated a reduction in biomarkers linked to myocardial injury, manifested anti‐inflammatory and antifibrotic effects, and induced alterations in myocardial energy metabolism. This is the first report of CDMOFs‐based oral delivery to improve the TSC bioavailability and efficacy. The utilization of CDMOFs@TSC resulted in superior therapeutic outcomes in comparison to standalone TSC by optimizing pharmacokinetics and precise targeted delivery. These results highlight the clinical potential of CDMOF as porous carriers to enable oral delivery of natural products for CHF therapy.

Experimental Study and Mechanism Analysis of Paraffin/Sisal Composite Phase Change Energy Storage Fiber Prepared by Vacuum Adsorption Method.

Sisal fiber exhibits a fibrous and porous structure with significant surface roughness, making it highly suitable for storing phase change materials (PCMs). Its intricate morphology further aids in mitigating the risk of PCM leakage. This research successfully employs vacuum adsorption to encapsulate paraffin within sisal fiber, yielding a potentially cost-effective, durable, and environmentally friendly phase change energy storage medium. A systematic investigation was carried out to evaluate the effects of sisal-to-paraffin mass ratio, fiber length, vacuum level, and negative pressure duration on the loading rate of paraffin. The experimental results demonstrate that a paraffin loading rate of 8 wt% can be achieved by subjecting a 3 mm sisal fiber to vacuum adsorption with 16 wt% paraffin for 1 h at -0.1 MPa. Through the utilization of nano-CT imaging enhancement technology, along with petrographic microscopy, this study elucidates the mechanism underlying paraffin storage within sisal fiber during vacuum adsorption. The observations reveal that a substantial portion of paraffin is primarily stored within the pores of the fiber, while a smaller quantity is firmly adsorbed onto its surface, thus yielding a durable phase change energy storage medium. The research findings contribute to both the theoretical foundations and the available practical guidance for the fabrication and implementation of paraffin/sisal fiber composite phase change energy storage mediums.

A Multilayer Nested Space Ray Telescope Assembly and Adjustment System Based on Online Monitoring Feedback

In order to adapt to the rapid development of deep space exploration, pulsar navigation and space astronomical observation technology, the development of high-efficiency and high-performance X-ray space telescopes has become one of the hotspots for research in the fields of autonomous spacecraft navigation and astronomical observation. Since the X-ray multilayer nested mirror shells are thin-walled and deformable cylindrical structures with high requirements for surface shape accuracy, a slight change in the position or surface shape will lead to a reduction in the focusing imaging quality, so it is necessary to develop a high-precision assembly and adjustment system based on closed-loop real-time monitoring. In this paper, a multi-layer nested space ray telescope assembly and adjustment system with online monitoring feedback is developed, and a method for precision assembly and adjustment of multi-layer nested mirror shells based on online real-time detection and feedback is proposed, which specifically includes key innovative assembly technologies such as three-dimensional face shape measurement, flexible vacuum adsorption, precision adjustment that have been broken through in the process, and the imaging quality of the focused spot of the mirror shells is evaluated and analyzed in the end. The results of the experiment indicate that the assembly and adjustment of the multilayer nested mirror shells can effectively complete the high-precision assembly, and the relevant results can provide a certain reference significance for the further enhancement of the assembly and adjustment performance of the multilayer nested mirror shells.

Preparation and steady-state heat transfer characteristics analysis of building insulation phase change composite material

The compatibility of Ba(OH)2?8H2O with aluminum alloy and copper after 50 heating cycles was studied using SEM and high power X-ray diffraction technique. Analyze the effect of temperature on thermal stability. The results show that Ba(OH)2?8H2O has some corrosion resistance to aluminum alloys and is similar with copper. The Ba(OH)2?8H2O/foam copper phase transition composites were prepared by a simple vacuum adsorption filling method. The experimental process of phase change energy storage device with and without copper foam was established, and the continuous heat transfer and transformation of Ba(OH)2?8H2O/foam copper phase change composites were carried out at room temperature. The results show that compared with pure Ba(OH)2?8H2O, Ba(OH)2?8H2O/foam copper phase converter has faster heat transfer and better thermal conductivity, effectively reducing the supercooling effect of Ba(OH)2?8H2O. Heat transfer experiment at high temperature shows that the heat capacity of Ba(OH)2?8H2O/foam copper phase changes with the increase of temperature. When the temperature of the zone is higher than the material phase changes in temperature, some insulation measures should be taken for phase shifting components.

Silicon/Silicon Carbide/Graphite Composite Anode Material for Rechargeable Lithium-Ion Batteries by High-Temperature Vacuum Adsorption Method

Recently, the electrode materials for next-generation lithium-ion batteries (LIBs) draw widespread attention on storing reversibly the electrical energy. For this issue, the expanded graphite and silicon particles are chosen to generate silicon/silicon carbide/graphite composite anode material using a high-temperature vacuum adsorption method. The prepared composites are measured by X-ray diffraction, transmission electron microscopy, and Raman spectra, et al. The composites are cycled at a current density of 50 mA g-1, in order to observe their potential specific capacity. An initial charge capacity is 566.5 mAh g-1, and its initial Coulombic efficiency is 97.4 %. The reversible specific capacity keeps at 502 mAh g-1 after 80 cycles, displaying a capacity retention of 88.7%

Enhancing the comprehensive corrosion resistance of waterborne epoxy coatings：Combination of Bimetal Nanocontainer ZIF-8-Ce and g-C3N4

In this study, we describe the synthesis of GP (g-C3N4@PDA) nanosheets via the encapsulation of g-C3N4 nanosheets with polydopamine (PDA). This encapsulation process serves to enhance the dispersion of the nanosheets in water, while also creating reaction sites for the subsequent loading of nanocontainers. Consequently, the GP nanosheets function as scaffolds for the in situ growth of pH-responsive ZIF-8-Ce nanocontainers, leading to the formation of GPZC (g-C3N4@PDA@ZIF-8-Ce) composite nanomaterials. Significantly, the porous structure of the g-C3N4@PDA@ZIF-8-Ce nanocontainer offers adsorption sites for benzotriazole (BTA). Through vacuum adsorption of a specific amount of benzotriazole, we successfully synthesize the composite nanomaterial GPZCB (g-C3N4@PDA@ZIF-8-Ce-BTA), which exhibits remarkable barrier and self-healing properties. To evaluate the comprehensive corrosion resistance of the composite coating incorporating GPZCB, a series of relevant performance tests were conducted. In the electrochemical test, the failure time of the GPZCB/sample was extended by 15 d. Additionally, the coating's durability time in the salt spray test was prolonged by 200 h. Importantly, GPZCB/WEC samples demonstrated rapid self-healing capabilities within a mere 4 h interval following coating breakage. Together, our study underscores the typical barrier properties and self-healing capacities of the developed composite coatings featuring GPZCB, accentuating their immense potential in delivering advanced corrosion protection across diverse applications.

Effect of different microcapsule types on the wear mechanism of PTFE/aramid fiber composite liners

AbstractIn this study, three different methods based on vacuum adsorption, solvent volatilization, and Pickering emulsion were utilized to prepare microcapsules with the core material of PAO40 and the wall materials of SiO2, polysulfone (PSF), and PSF/SiO2 composites, respectively. PTFE/Kevlar fabric liners were modified by PAO40/SiO2 microcapsules (PSMS), PAO40/PSF microcapsules (PPMS), and PAO40/PSF/SiO2 microcapsules (PPSMS). The effect of microcapsules based on different wall materials on the tribological properties of liners was investigated by friction and wear tester under low‐speed and heavy‐load conditions. The anti‐friction and anti‐wear mechanisms of several microcapsule types on the liners were systematically investigated. The results showed that PPMS induced the most significant enhancement in anti‐friction properties of liners when compared to pure liner resulting in a 19.4% reduction in coefficient of friction (COF). PSMS was found to reveal much better wear resistance of liners, as evidenced by 75% increase in wear rate. PSMS and PPSMS not only release lubricating oil after the break of microcapsules under the friction action to lubricate, but also generate a cavity to store abrasive debris for liner wear reduction. Nonetheless, PPMS only released the oil onto the friction surfaces for lubrication. PSF as the microcapsule wall material could not contribute to the formation and promote wear resistance of transfer films. SiO2 as a microcapsule wall material participates in the formation and enhances the wear resistance of transfer films. The findings obtained are anticipated to improve the reliability and broaden the range of applications of liners in aerospace and other industrial fields.Highlights Three microcapsules all improve the tribological properties of the liners. Anti‐friction and wear‐resisting mechanism of three microcapsules in liners. SiO2 as wall material can increase the wear resistance of transfer films. PAO40 in microcapsules has antifriction effect at the friction interface.

Novel insights into the microstructure of Al-BHA on the surface of ilmenite

In the process of flotation recovery of metal oxide ore, the complexes obtained by premixing metal ions with benzohydroxamic acid are often used as collectors. The study of aluminum (III) -benzohydroxamic acid (Al-BHA) system is not perfect. In order to study the chemical properties, microstructure and adsorption mechanism of Al-BHA on mineral surface, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and density functional theory (DFT) were used. The analysis of FTIR confirmed the chemisorption of Al-BHA onto the ilmenite. AFM results show that the coverage of Al-BHA on the surface of ilmenite is obviously better than that of BHA. According to Fukui function and frontier orbital theory, the chemical activities of Al-BHA are greater than those of BHA. In addition, aluminum atom is the active center of Al-BHA. The bonding model of the collector and (104) ilmenite surface showed that the vacuum adsorption energy of Al-BHA was higher than that of BHA, and the bridge site adsorption form is the most stable. Overall, it is possible to apply Al-BHA with higher activity to ilmenite flotation.

Preparation and thermal properties of phase change energy storage composite material based on modified fly ash

Fly ash (FA) is a kind of porous solid waste from coal-fired power plant, It is nominated as adsorption carrier for solid-liquid phase change material (PCM), While shape-stabilized composite phase change materials (SSCPCM) prepared directly has low thermal performance due to limited adsorption capacity of FA. Therefore, modification methods have become increasingly attractive, and four modification methods were investigated to improve the adsorption capacity of FA. Modification treatment experiment proved that the surface structure of FA is significantly corroded. Test analysis displays that the surface microspheres in FA have abundant particles and pores by destroying the Si–O–Si and Si–O–Al network structures. The mass ratio of Al/Si increased from 0.59 to 0.726, and the specific surface area of FA has been greatly increased. Experimental results indicate that alkali modification followed by high-temperature calcination is the desirable process for FA. For obtaining high thermal performance materials, two kinds of SSCPCM were prepared according to the mass ratio of 65:35 by vacuum adsorption while Alkali modified FA serves as carrier, binary eutectic of lauric acid-stearic acid (LA-SA) and lauric acid-myristic acid (LA-MA) serves as PCM respectively. The LA-SA/AFA-OH (NaOH alkali leaching treatment for FA) and LA-MA/AFA-OH (NaOH alkali leaching treatment for FA) could reach 54.49 J/g and 47.15 J/g and the phase transition temperature (PTT) is 37.45 °C and 32.36 °C, respectively. The SSCPCM has good thermal, chemical and morphological stability over 500 thermal cycles, while the LA-MA/AFA-OH had higher stability and less thermal performance slightly. Research finding provide a feasible process for composite modification of FA, and application scope is extended due to high thermal performance of composites.

Research on stability control strategy of adjustable pressure wall-climbing robot based on adsorption identification

In order to solve the problem that it is difficult to accurately model the complex fluid domain in the negative pressure chamber of the robot in the process of wall climbing, and thus cannot quickly and steadily adsorb, a double closed-loop control strategy based on parameter identification and particle swarm optimization is proposed in this paper to improve the speed and stability of the adsorption response of the robot in the process of wall climbing. Firstly, a vacuum negative pressure wall climbing robot with a spring pressure regulating structure is developed, and the critical conditions of the robot’s instability are solved by mechanical analysis. Then, the rigid-flexible coupling model of the whole machine was established based on mass, spring and Maxwell viscoelastic elements. The model parameters of the adsorption system were identified by vacuum adsorption test. Compared with the experimental data, the accuracy of the model was more than 80%. On this basis, PID controller is used to adjust the adsorption response speed of the robot, a double closed-loop stable adsorption control strategy is designed, and the control parameters of the adsorption system are adjusted by using the dynamic weight standard particle swarm optimization algorithm. Finally, simulation and prototype tests show that, the proposed control strategy can shorten the static and dynamic response time of the adsorption system by about 3.5 s and 1.4 s, the flow response time by about 1.15s, the maneuvering performance of the whole system is improved by about 26%, and the parameter overshoot and steady-state error are lower, which provides a theoretical reference for the stability control and engineering application of the wall-climbing robot.