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A novel ultrasonic burnishing (UB) system with a flat tool using a piezoelectric longitudinal transducer (PLT) is proposed. High-precision no-feeding mark planar burnishing can be achieved by the compact system with a size of only 280 mm 224 mm 558 mm without the need for machine tools. Above all, the structure of the burnishing system is presented and the operation principle is analyzed in detail. A resonant frequency design method of the PLT with a tool head is discussed. Based on thisthe PLT achieves the expected resonant frequency precisely. Subsequently, the test system for the PLT is built and the resonant frequency and vibration amplitude are tested, which are in good agreement with the simulation results. Ultimately, the UB experiments are carried out and the results indicate that the surface roughness of the workpiece is reduced from Ra 1.6 m to Ra 0.182 m, which is reduced by 88.31%. Furthermore, the surface topography shows that the surface without the feeding mark is generated, which is beneficial to improve the burnishing accuracy and expand the application in ultra-precision processing.

To enable mobile robots to effectively deal with the emergency of visual contamination, contingency planning based on case-based reasoning (CBR) was performed in this paper. First, for a wheeled mobile robot (WMR) equipped with a chameleon-inspired visual system, a target search model in chameleon-inspired binocular negative correlation movement (CIBNCM) mode was established. Second, a CBR-based contingency planning model of visual contamination for WMRs was established, where the reasoning process using CBR for visual contamination was analyzed in detail. Third, through the analysis of environment perception when visual contamination occurs, a perception model in chameleon-inspired visual contamination for WMRs was built. Finally, to validate the proposed approach, a contingency planning experiment scheme for visual contamination was designed based on the robot’s general planning of target tracking, and the experimental result is discussed. The proposed CBR-based contingency planning approach for visual contamination can reason out effective solutions corresponding to the contamination situations. The rationality of the approach was verified by experiments with satisfactory results. Moreover, compared with the contingency planning method based on rule-based reasoning, the accuracy of target retracking after the robot visual system is contaminated is significantly higher for the CBR-based contingent planning method used in this paper.

A ring-shaped linear piezoelectric actuator with three driving teeth is proposed and designed based on an axial-radial bending coupling vibration mode. The coupling vibration mode is neither pure axial bending mode nor pure radial bending mode, but an axial-radial bending hybrid one, which is generated by only one group of PZT elements and one excitation signal under an asymmetric fixed boundary condition. The working principle of the proposed actuator is similar to the opening and closing actions of the three-petal mouth of a rabbit, which is analyzed by finite element method (FEM). Then, the coupling vibration mode is verified by a scanning laser Doppler vibrometer after the fabrication of a prototype. Experimental results show that the prototype can achieve a maximum velocity of 60.46 mm/s and a displacement resolution of 0.5 m, and the velocity of the linear actuator can be smoothly adjusted in a wide range of 0.00560.46 mm/s. In addition, the actuator can drive a hollow cylinder mover along different slopes without other auxiliary structures. The simulated and experimental results confirm that the proposed ring-shaped actuator is feasible without any guiding structure, which has great potential to realize further miniaturization of linear piezoelectric actuators.

With the rapid expansion of the natural gas consumption market worldwide, methanation of coal- or biomass-derived syngas for production of synthetic natural gas (SNG) is gaining considerable interest. In order to solve the problem of natural gas “peak shaving”, adjusting product distribution of the SNG plant is an efficient method to meet the demand fluctuation of natural gas in peak and off season. Herein, the conversion of syngas to SNG (CH4) and co-production of liquid fuels (C5+) over bimetallic Ni-Co catalysts was investigated at industrially relevant conditions. The effects of integration manner of the Ni-Co components, Ni/Co mass ratio, and the operating conditions on the catalytic performance were investigated. Due to the synergistic interaction between Ni and Co, silica supported Ni-Co bimetallic catalyst shows higher activity and total yield of methane and liquid fuels compared to the physically mixed sample. In addition, a good balance between Ni and Co content is crucial for the high efficiency co-production of SNG and liquid fuels. It is found that the optimum operating range in the present study is 550–578 K, H2/CO = 3, 3.0 MPa and W/F = 5 gcat h mol−1, in which more than 80 % total yield of methane and liquid fuels can be obtained on the 2Ni-1Co/SiO2 bimetallic catalyst. Moreover, it shows good thermal stability during the 55 h reaction time. All catalysts were examined by XRD, TEM, H2-TPR and XPS.

Bacterial cellulose (BC) is widely used in the food industry for products such as nata de coco. The mechanical properties of BC hydrogels, including stiffness and viscoelasticity, are determined by the hydrated fibril network. Generally, Komagataeibacter bacteria produce gluconic acids in a glucose medium, which may affect the pH, structure and mechanical properties of BC. In this work, the effect of pH buffer on the yields of Komagataeibacter hansenii strain ATCC 53582 was studied. The bacterium in a phosphate and phthalate buffer with low ionic strength produced a good BC yield (5.16 and 4.63 g/l respectively), but there was a substantial reduction in pH due to the accumulation of gluconic acid. However, the addition of gluconic acid enhanced the polymer density and mechanical properties of BC hydrogels. The effect was similar to that of the bacteria using glycerol in another carbon metabolism circuit, which provided good pH stability and a higher conversion rate of carbon. This study may broaden the understanding of how carbon sources affect BC biosynthesis.

Stick-slip rotary piezoelectric actuators (SRPAs) are commonly used nowadays. However, most of them achieve high velocity by high exciting frequency, which causes the problems of wide power-source passband requirement and the wear of actuators. Moreover, their further applications are limited, due to the poor motion stability caused by the backward motion. To solve the problems, the stick-slip process is analyzed with kinematics, indicating that the large step contributes greatly to SRPAs for achieving high velocity under low operating frequency and backward motion elimination. Then a large-step SRPA is proposed, fabricated, and tested. The experiments show that under the sawtooth signal with 100 V and 400 Hz, the prototype can reach a maximum velocity of 1.854 rad s−1, benefiting from the large step (above 4.636 mrad). While other works require the exciting frequency of several kilohertz to reach the same level of velocity. Additionally, by increasing the step, the backward ratio decreases from 14.43% to 8.89% at the frequency of 1 Hz, and the minimum no-backward frequency decreases from 120 Hz to 60 Hz. The results indicate the effectiveness of the large step for solving the problems, which is significant for the design of SRPA.

A novel piezoelectric stack for rotary motion using d 15 working mode is proposed, fabricated, and tested in this article to achieve the high stiffness and high precision of rotation. This piezoelectric stack is fabricated by bonding process from only two components—lead zirconate titanate ceramics and electrodes, which is beneficial to realize the simple structure. A theoretical model based on the shear deformation theory is established to predict the static output performances. And the simulation with the finite-element method is adopted to evaluate the dynamic characteristics. An experimental system is built to verify the design and study the performances of the piezoelectric stack. The experimental results indicate that the static output angle changes from −13.25 to +13.33 μ rad, whereas the exciting voltage changes from −300 to +300 V, with good linear relationship and high repeatability accuracy. Under the condition of changing the exciting voltage by the step of 0.5 V, the stable resolution is measured to be higher than 0.022 μ rad. The large load capacity and width frequency response are verified, which reflect the high stiffness of the proposed piezoelectric stack. The proposed piezoelectric stack achieves accurate and stable rotary output motion with high resolution, rapid response, and large load capacity. Besides, the stack has regular shape and simple structure, and therefore, it is suitable to be integrated in the equipment in the fields of micro–nano manipulations, piezoelectric ultrasonic motors, etc.

Coconut milk is a traditional subtropical food, but its quality and flavor stability are the biggest challenge for promotion and commercialization. In this study, the effect of dynamic high-pressure microfluidization (DHPM) on texture and flavor properties of coconut milk was investigated under different pressures. The mean particle size decreased from 24.04 ± 1.17 μm (blank sample) to 8.21 ± 0.11 μm, reaching the minimum at 18000 psi. Microfluidization technique has positive effect on the taste of coconut milk, reducing the bitterness value from 13.39 ± 0.23 to 11.50 ± 0.20 (p > 0.05) using electronic tongue; simultaneously, the other tastes were retained. The flavor of coconut milk is less affected by pressure, and the flavor is essentially not lost in the appropriate pressure range. This work provides a new understanding of quality and flavor changes of coconut milk using DHPM in the future processing process.

The emulsifying and antioxidant properties of chicken protein hydrolysates for the physical and oxidative stabilization of chicken oil‐in‐water emulsion were investigated. The chicken protein pepsin hydrolysates obtained at reaction temperature of 33℃, 1.8% enzyme addition, liquid–solid ratio of 5:1, and reaction time of 4h, showed the DPPH radical scavenging rate of 92.12% and emulsion stability index of 0.07. The hydrolysate exerted significantly improved antioxidant activity and emulsion ability compared to the native chicken protein. The amino acid composition analysis indicated that the contents of hydrophobic amino acids including tyrosine, phenylalanine, and tryptophan were increased after hydrolysis, which contributed to the higher hydrophobicity and antioxidant activity of chicken hydrolysates. The results suggested that the chicken protein hydrolysates could be used as an alternative protein emulsifier for the production of oxidatively stable chicken oil‐in‐water emulsion., The chicken hydrolysates exhibited good antioxidant activity and emulsion ability, which can be used to protect chicken oil from oxidation.

A U-shaped stepping piezoelectric actuator featuring low motion coupling is proposed, fabricated and tested. The actuator contains four similar piezoelectric actuation units (PAUs): two of them are used as the clamping units, while the other two act as the pushing units. The sliders and brackets supporting the clamping units can strongly suppress the motion coupling. The actuator can move the runner twice in each cycle with the operating principle similar to an inchworm. Static models are developed to calculate the step length and clamping force of the proposed actuator. A prototype is fabricated and its mechanical output characteristics are measured. The measured step length and clamping force agree well with the calculated results by the static model. The operating principle is verified by the experiment results, and the motion coupling ratio is 4%. The output speed linearly depends on the voltage applied on the pushing units, which indicates that the proposed actuator is very suitable for speed control. The working frequency has positive effect on the speed in range from 0.05 Hz to 6.25 Hz, whereas negative effect is found over 6.25 Hz. The prototype achieves a maximum thrust force of 189.7 N and a maximum speed of 273.4 μm/s.

A piezoelectric robot with four parallel legs operating in rowing mechanism was presented and tested. The driving feet of the legs moved in a triangular trajectory, and a pair of legs on the same axis operated like rowing to move the robot step-by-step through the static friction forces between the driving feet and platform. A kinematic model with respect to the motion of the piezoelectric legs was established based on the Timoshenko beam theory and Galerkin procedure, which was used to design and optimize the structure of the robot. A prototype was fabricated and its experimental system was established. The motion trajectory of one driving foot was measured, which agreed well with the calculated results using the kinematic model in terms of both magnitudes and trajectory. A nanopositioning ability was achieved with a resolution of 16 nm. The experiment results showed that the output speed was linearly related to the voltages of the excitation signals, and motions along any directions could be achieved by changing the applied voltages. The prototype achieved maximum output speeds of 584 and 614 μ m/s along the X and Y axes, respectively, under voltage of 400 Vp-p and frequency of 100 Hz. Furthermore, a carrying capacity of 25 kg was achieved. The proposed piezoelectric robot could be used to transport heavy devices with nanopositioning accuracy.

A piezoelectric actuator using three sandwich longitudinal vibrators is proposed and tested. The two horizontal vibrators are parallel to each other and orthogonal to the vertical vibrator. The ends of the two horizontal vibrators serve as the four driving feet. The actuator has a simple fabricating process, which will shorten the period of fabrication. Two modes of the actuator are used to get the elliptical trajectories on the driving feet. The frequencies of the two modes are tuned to be about 21.60 kHz with modal analysis by the finite element method (FEM). The operating principle is also examined with transient analysis by FEM. A prototype is fabricated and its vibration characteristics are verified by using a scanning laser Doppler vibrometer. The prototype shows the best mechanical performance with the optimum working frequency and phase difference of 18.50 kHz and 60°, respectively. The typical output of the prototype is a no-load speed of 439.41 mm/s, a maximum thrust of 40 N, and a maximum power of 5.01 W at the voltage of 200 ${V} _{\mathrm {P-P}}$ . The mechanical characteristics of the prototype show that the exciting voltages can be used for the speed control due to the approximately linear relationship between them.

A planar piezoelectric actuator using bending-bending hybrid modes is proposed. The actuator is composed four uniform transducers that can bend in the horizontal and vertical directions dependently. The actuator can operate in two modes: dynamic mode and quasi-static mode. The dynamic mode uses the hybrid bending resonance modes to achieve a large travelling range with high speed; the quasi-static mode uses the quasi-static horizontal bending to achieve a micrometre travelling range with nanometer resolution. The operating principle is discussed and simulated by finite element method (FEM). Maximum linear and rotary speeds of 19.8 mm/s and 0.266 rad/s are obtained under a voltage of 400 Vp-p and frequency of 11.86 kHz in the dynamic mode. When operating in quasi-static mode, there is a linear relationship between the output displacement and voltage, linear and rotary displacement resolutions of 16 nm and 0.198 μrad are obtained. The actuator can accomplish large travelling range with nano-positioning ability.

Bacterial cellulose (BC) is widely used in the food industry for products such as nata de coco. The mechanical properties of BC hydrogels, including stiffness and viscoelasticity, are determined by the hydrated fibril network. Generally

A linear ultrasonic motor (USM) with two piezoelectric stators using the combination of two third bending vibration modes is proposed in this study, two orthogonal bending modes can simplify the effort of frequency degeneration. A square runner is driven by two stators through elliptical motions of their driving feet. Three driving feet in each stator are located at its middle and both ends, they vibrate with the same elliptical trajectory and push the runner together for improving the output performance. The finite element method (FEM) is adopted to optimize structural configuration of the stator, which ensures the amplitude uniformity of three driving feet. A prototype of the proposed USM is manufactured and its mechanical characteristics including velocity versus exciting voltage and velocity versus carrying load are tested in sequence. The tested results show that the maximum no-load velocity of the prototype is 117.22 mm/s at the exciting voltage of 65 Vp-p, and the maximum carrying load of the prototype is 350 g when the exciting voltage is 60 Vp-p. The tested results confirm that the developed USM has the advantages of simplified frequency degeneration in structure design and low exciting voltage.

A novel two-DOF piezo-driven fast steering mirror (PFSM) with high stiffness and good decoupling characteristic was proposed. This PFSM could realize rotary motions around X-axis and Y-axis by differential push–pull structure with four piezoelectric stack actuators (PSAs) arranged in cross and orthogonal state, and its lateral stiffness was high enough to overcome the problem that PSA was easy to be destroyed by large lateral force. The PFSM was designed and its working principle was described in detail. The static model was established to analyze the stiffness characteristic of the structure and precisely predict the output angles. The finite element method (FEM) was performed to verify the effectiveness of the proposed structure and static model. A prototype of the PFSM was fabricated, and an experimental setup was established. The experiments showed that the proposed PFSM could achieve rotary motion ranges of 2.33 mrad around X-axis and 2.25 mrad around Y-axis under the voltage of 120 V, respectively. And the resolution was measured as high as 0.28 μrad with the voltage increment of 0.2 V. Furthermore, the first order resonance frequency was measured as 4578 Hz and a good decoupling characteristic was obtained, the coupling errors of both two axes were below 0.75%. The two-DOF PFSM could be applied to the laser communication and the adaptive optics system based on its merits of high stiffness, high resolution and good decoupling characteristic.

A precise rotary positioner driven by piezoelectric bimorph elements with simple structure and high resolution was proposed, fabricated and tested in this work. The dimensional design was completed according to the theoretical model, and the simulations were conducted with finite element method. A prototype and an experimental set-up were fabricated to conduct some experiments. The experimental results showed that the positioner had a small mass of 20.5 g, and the output angle fitted a good linear relationship with the exciting voltage. Besides, the repeatability was measured as 0.180″ (0.873 μrad), and the resolution was higher than 0.0252″ (0.122 μrad), which reflected the high precision of the positioner. The dynamic performances were measured and the load characteristic was calibrated as well. Based on good extendibility, more bimorphs could be added to improve the load capability or increase the motion stroke. The proposed positioner had a good prospect in the field of precise rotary positioning.

A novel U-shaped piezoelectric ultrasonic motor that mainly focused on miniaturization and high power density was proposed, fabricated, and tested in this work. The longitudinal vibrations of the transducers were excited to form the elliptical movements on the driving feet. Finite element method (FEM) was used for design and analysis. The resonance frequencies of the selected vibration modes were tuned to be very close to each other with modal analysis and the movement trajectories of the driving feet were gained with transient simulation. The vibration modes and the mechanical output abilities were tested to evaluate the proposed motor further by a prototype. The maximum output speed was tested to be 416 mm/s, the maximum thrust force was 21 N, and the maximum output power was 5.453 W under frequency of 29.52 kHz and voltage of 100 Vrms. The maximum output power density of the prototype reached 7.59 W/kg, which was even greater than a previous similar motor under the exciting voltage of 200 Vrms. The proposed motor showed great potential for linear driving of large thrust force and high power density.

Inspired by a way of rowing, a new piezoelectric driving quadruped micro-robot operating in bending-bending hybrid vibration modes was proposed and tested in this work. The robot consisted of a steel base, four steel connecting pins and four similar driving legs, and all legs were bonded by four piezoelectric ceramic plates. The driving principle is discussed, which is based on the hybrid of first order vertical bending and first order horizontal bending vibrations. The bending-bending hybrid vibration modes motivated the driving foot to form an elliptical trajectory in space. The vibrations of four legs were used to provide the driving forces for robot motion. The proposed robot was fabricated and tested according to driving principle. The vibration characteristics and elliptical movements of the driving feet were simulated by FEM method. Experimental tests of vibration characteristics and mechanical output abilities were carried out. The tested resonance frequencies and vibration amplitudes agreed well with the FEM calculated results. The size of robot is 36 mm × 98 mm × 14 mm, its weight is only 49.8 g, but its maximum load capacity achieves 200 g. Furthermore, the robot can achieve a maximum speed of 33.45 mm/s.

A U-shaped linear piezoelectric ultrasonic motor (PUM) was proposed, designed and tested in this work, in which three longitudinal transducers were used together to achieve the linear driving by two feet synchronously. Longitudinal vibrations of the transducers were generated with certain temporal shift to form the desired elliptical movements on the two driving feet. Finite element method (FEM) was used to accomplish the design process, in which the resonance frequencies of the transducers were tuned to be very close, and the movement trajectories of the driving feet were gained to show the feasibility initially. Then, a prototype was fabricated and tested to verify the proposed design further. The resonance frequencies of the two vibration modes of the prototype were tested to be about 30.184 kHz and 30.227 kHz by using the Scanning Laser Doppler Vibrometer (SLDV). The optimal working frequency of the prototype was tested to be about 29.35 kHz. The maximum output speed and maximum thrust force were tested to be about 321.6 mm/s and 12 N, respectively.

There is a paucity of studies on the immunomodulatory properties of fruit extracts of emblica with the emphasis on lymphocytes. Therefore, the aim of the study was to evaluate the immunomodulatory properties and anticancer potential of six phenolic compounds from emblica fruit by in vitro proliferation assay. Effects of these compounds on splenocyte proliferation and the cytotoxicity to both human breast cancer cell (MCF-7) and human embryonic lung fibroblast cell (HELF) were determined by the MTT method. Significantly stimulatory effects ( P 0.05 ) were found for geraniin and isocorilagin. The concentration of geraniin, quercetin 3-β- d -glucopyranoside, kaempferol 3-β- d -glucopyranoside, isocorilagin, quercetin, kaempferol and rutin to obtain 50% of stimulatory effect was 56, 123, 242, 42, 73, 93 and 92 μg/ml, respectively. The assay of anticancer activities suggested that geraniin and isocorilagin exhibited higher cytotoxicities than other compounds against MCF-7 with IC 50 of 13.2 and 80.9 μg/ml, respectively. Isocorilagin exhibited a strong cytotoxicity to HELF cell with IC 50 of 51.4 μg/ml. Geraniin, quercetin, kaempferol and their glycosides had weak cytotoxicity against HELF cells. Paclitaxel showed a strong cytotoxicity to MCF-7 and HELF with IC 50 of 6.8 and 14.5 μg/ml, respectively. These findings are in line with the reported potent antioxidant activity. These results suggested that the antitumour activity of these compounds might be achieved by immunomodulatory properties which could partially be attributed to their antioxidant activity.

We propose an automatic evaluation method for the machine translations system. The method extends the idea of skip-bigram with unequal length grams and dependency relations. The unequal length relax the constrains of the previous method and the dependency relations qualify the grams with linguistic knowledge. The effectiveness of the new method is approved by the experimental results with various settings on sentence level.