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Robot-assisted minimally invasive surgery (MIS) has shown tremendous advances over the traditional technique. A crucial challenge for developing a MIS robot is the kinematic design of the remote center-of-motion (RCM) mechanism. In this paper, a class of spatial RCM mechanism is analyzed. They are obtained by generating virtual parallelograms. The main process is to construct a line that passes through a fixed point under the mechanical constraint. The axis of the surgical tool is then constrained to parallel with that line. Hence, due to the geometrical feature of the parallel lines, the axis of the surgical tool will always pass through a fixed point, i.e., the RCM point. Due to the specially designed structure, the fixed point does not need to be physically belonging to the mechanism. The geometrical analysis method is employed to obtain the closed-form solution of the forward kinematics of the proposed mechanisms. Due to the high load capacity of parallel mechanism, the robots based on the proposed RCM mechanisms have promising applications as an external positioner to be used in robotic single-port surgeries.

This paper presents a Fiber Bragg Grating (FBG)-based torque sensor with high sensitivity and miniature size for MIS instruments and multi-finger hands. The proposed sensor design mainly consists of a torque-sensitive flexure structure and two diagonally arranged optical fibers embedded with FBG sensing elements. An improved hollow hexaform structure with flexible hinges has been utilized to design the torque-sensitive flexure with an excellent linear measurement range and a solid capacity to resist non-torsion loading. Two optical fibers with an FBG inscribed each adopt a two-point gluing configuration with a tightly stretched status, and they are arranged diagonally along the hyperboloid surface. This configuration can obtain improved sensitivity and resolution and avoid the drawbacks of FBG chirping and low repeatability. Finite element modeling (FEM)-enabled simulation has been implemented to perform design optimization for further sensor sensitivity improvement and performance investigation. The prototyped sensor has been calibrated and achieves a high resolution of 0.062N $\cdot $ mm within [−100, 100N $\cdot $ mm] and excellent linearity with a small linearity error of 0.68%. The crosstalk experiments on the bending moment of Mx and My and the axial force have been conducted to validate the anti-interference capacity on the basis of the small values of 0.47%, 0.31%, and 1.78%. The proposed design also supports convenient customization to achieve the adjustable measuring range and torque sensitivity, which has been validated by another sensor version with a resolution of 0.26 $\text{N}\cdot $ mm within [−500, 500N $\cdot $ mm].

Traditional commercial master devices and specialied serial master devices meet insufficient workspace, low intuitiveness, low stiffness, and poor accuracy during master-slave mapping for robot-assisted flexible ureteroscopy (FURS).This paper presents a 3-DoF master device for FURS. A 2-DoF parallel mechanism was designed and utilised in the master device for higher stiffness based on requirements analysis. A Back Propagation Neural Network was built for the forward kinematics of the parallel mechanism during master-slave mapping. Analysis of mechanical characteristics was carried out for the usability of the master device. A contrast experiment on the phantom was conducted to evaluate the performance between the proposed master device and a previous one.The completion time for each trial of the proposed master devices is shorter than that of the previous master serial device. Meanwhile, the proposed device provides a more comfortable operating style than the previous one.The proposed 3-DoF configuration for the master device is with more intuitive performance. A better comfort level indicates its usability in clinical applications.

Recently, sand fences, made of high density polyethylene (HDPE) board, which is resistant against harsh plateau environmental conditions, could possibly be used to control the wind-blown sand along the Qinghai section of the Golmud-Korla Railway. In this paper, wind tunnel simulation was performed on the protective effect of multiple rows of HDPE board sand fences on wind-blown sand. Two parameters have been used to reflect the protective effect of sand fences, that is, windproof efficiency and sand control efficiency, referring to the reduction rates of wind speed at a height of 0.04 m and sand flux in a run of test with the fence compared those in the control run of test without it, respectively. The test results showed that when the porosity was 30%, the single-row sand fence had the best wind proof and sand control efficiency with respective values of 46% and 65.3%. The windproof efficiencies of double-row and triple-row sand fences at 20H were 59% and 62%, respectively. Compared with the windproof efficiency of the single-row sand fence, those of the two-row and three-row fences increased by 13% and 16%, respectively; The maximum sand control efficiency of the double-row and triple-row sand fences were 92.1% and 96.5%, increased by 26.8% and 31.2%, respectively, compared with that of the single-row sand fence. This study indicates that the sand control efficiency after adding one or two rows was not double or triple that of the single-row fence, while the first-row sand fence played a major protective role. Compared with the double-row sand fences, the effect of the third row sand fence in triple-row sand fences is limited, and thus double-row HDPE board sand fences with the porosity of 30% are recommended to control wind-blown sand along the Qinghai section of the Golmud-Korla Railway.

A new UHMWPE-based conductive fabric was successfully prepared by radiation-induced graft polymerization and subsequent post-modification, followed by electroless deposition. The chemical structure and composition of modified UHMWPE fabrics were investigated in detail by ATR-FTIR, 29Si NMR, and XPS to confirm grafting and post-modification. After electroless deposition, the morphology, thermal stability, and crystal structure of original and modified fabrics were characterized by SEM, TG, DSC and XRD. Cu-deposited UHMWPE fabric exhibited much better thermal resistance than that of UHMWPE and Cu@UHMWPE-g-PAAc. In order to improve the oxidation resistance of copper-deposited fabric, nickel was processed on copper-coated UHMWPE fabric to protect the copper layer. An electromagnetic shielding effect test showed the nickel–copper coated UHMWPE fabric could shield 94.5% of the electromagnetic wave in the frequency range of 8–12 GHz. This work provides an approach for addressing the issue of poor thermal resistance of metal-coated polymeric materials due to the inherent low melting point of the organic support.

The master manipulator of flexible ureteroscopy (FURS) robot system plays an important role in the master-slave control and its operating comfort influences the efficiency and quality of the robot-assisted surgery. The evaluation mechanism of operating comfort is commonly implemented based on the human joint movements and ignores the joint torque, which significantly influences on the surgical procedure and outcomes. This paper proposes an evaluation model of upper limb operating comfort based on joint torque for FURS robot through the Lagrange equation and NASA joint torque model. The reliability of the proposed evaluation model has been verified by the rapid upper limb assessment (RULA) by software Delmia and the muscle fatigue experiments on ureteroscopy by both of robotic and traditional manual approaches. The results indicate that the comfort index based on joint torque can well reflect the operating comfort for the ureteroscopy surgeon. Using the same with the evaluation model, the muscle fatigue experiments also show that the improved efficiency and quality of the master manipulator for FURS, which can facilitate to improve the design and control of the FURS robot system.

Based on Hamilton’s principle, a nonlinear differential equation considering the effect of dead loads is formulated for box beams. By using Galerkin method, the effect of dead load on the natural frequencies of box beams with various restraint conditions being simply supported, fixed at both ends, cantilevered and fixed at one end and simply supported at the other end is studied. The effects of major physical parameters, including the magnitude of dead load, sectional inertia moment and inertia radius, span length, and restraint conditions are discussed, and the natural frequencies are presented for these box beams, with the nonlinear effect of dead load taken into account. The results show that the deterrent effect of dead loads has significant effect on the increase of the natural frequencies of box beams. It is further observed that this behavior is more apparent at lower-order natural frequencies; the varying deterrent effect of dead loads relates to the stiffness of structures and is more significant for more flexible structures.

In this study, an amidoxime-appended zirconium metal-organic framework [Zr6O4(OH)4(BDC-NHCH2CH2C(=N–OH)NH2)6](UiO-66-AO, BDC = 1,4-benzenedicarboxylate) for efficiently and rapidly removing uranium from aqueous solution was fabricated through post-modifications. The chemical structure and composition of original and modified UiO-66 MOFs were investigated in detail. The principal factors affecting the adsorption of U(VI) ions have been investigated, including pH of the aqueous solution, contact time, temperature, and coexisting cations through batch adsorption experiments. The adsorption kinetics conformed to the pseudo-second-order model. It was found that the maximum adsorption capacity reached 232.8 mg/g at pH 5.0 and 328 K based on the Langmuir isotherm. The thermodynamics parameters revealed that this adsorption process was spontaneous and endothermic. The sorption experiment in a simulated nuclear industry effluent demonstrated a high adsorption efficiency (about 95.3%) and selectivity toward uranium. The extended X-ray absorption fine structure (EXAFS) analysis revealed the coordination mechanism of amidoxime-appended UiO-66 and uranyl.

Herein, we report on fabrication of a highly durable smart mesh with reversible superhydrophobicity-hydrophilicity, using a two-step surface modification and hydrothermal process for on-demand oil-water separation. This wettability of transformation can be achieved under lower voltage within a few seconds than the reported literatures. Such an on-demand operation could be beneficially applied to automated and remote operation of oil-water separation situations, which would be very useful for the treatment of various effluents, including those with low levels of radioactivity. The reversible wettability not only makes our material applicable in both “oil-removing” and “water-removing” situations, with a separation efficiency of 99%, but also effectively prevents the mesh film from being contaminated with oil. The material developed in this work retained its high separation efficiency after 10 alternate-use cycles, involving oil-removing and water-removing modes, and sonication for 20 min, demonstrating its high durability. Our study provides a new pathway to improve the interface binding force between ZnO nanorod arrays and its support without affecting electrowetting performance, thus potentially making a useful contribution to the design of novel devices based on electrowetting-driven oil-water separation.

The trade-off between increased heat resistance and deterioration of mechanical properties caused by excess heat-resistant additives limits the use of silicone rubber (SR) in cutting-edge applications and extreme conditions. In this study, a novel SR composite with ultrahigh thermal oxygen stability was developed by blending SR with a small amount of cobalt-based metal-organic framework (zeolitic imidazolate framework-67, ZIF-67). The addition of only 0.125–0.5 wt% (relative to the content of SR) of ZIF-67 to SR could effectively improve its thermal-oxidative stability. Specifically, after 12 days of aging, the retentions of elongation at break of ZIF-67/SR composite reached 28.3–60.7% of the original, while the maximum decomposition temperature of ZIF-67/SR was approximately 25–30 ℃ higher than that of pristine SR. The origin of these attractive characteristics of the ZIF-67/SR composites was investigated by carrying out electron spin resonance (ESR) and X-ray absorption fine structure (XAFS) analyses.

The robot-assisted natural orifice transluminal surgery (NOTES) typically involves applying the lengthy and slender continuum instruments/manipulators to get access to the target lesion sites, and then performs complex operations. However, due to the strong-nonlinearity of continuum robotic manipulators and the confined and tortuous anatomical paths, it’s difficult to establish accurate inverse kinematics (IK) model to achieve precise motion control and real-time shape sensing for accurately modeling their shapes. To tackle such difficulties, a model-free method based on neural network have been proposed to solve the IK problem and reconstruct the shape of a continuum manipulator at the same time using the training results from the electromagnetic (EM) tracking approach. For the IK problem, the relationship between the tip position and the corresponding cable lengths can be learned and for the shape estimation problem, the mapping from the cable lengths to the shape of the continuum robot can be established. A dataset of 500 random continuum manipulator postures was used to train the neural network, with recorded EM sensors-tracked positions logged synchronously to the cable lengths. Experiment results show the proposed model-free method could achieve high accuracy and reliable inverse kinematics and shape reconstruction outcomes.

The robot-assisted Natural Orifice Transluminal Endoscopic Surgery (NOTES) enables to perform complex and delicate operations along anatomical tortuous paths through natural orifices. Such emerging techniques also pose difficulties for the master manipulator design. Based on the requirement analysis and ergonomics for robotic NOTES systems that rely on a master-slave configuration, this work proposes a new type of master manipulator in a combined parallel and serial configuration, providing advantages in terms of improved stiffness and accuracy, large workspace, low damping ratio, easy implementation of force feedback. It has three degrees of freedom (DoFs) with one driving unit for each DoF, including translation and two rotation forms, and supports both passive mode and active mode, permitting force feedback in all the three DoFs. A simplified and improved parallel mechanism with a planar six-linkage configuration is proposed to achieve translational motion, and it adopts a rotational form to replace the traditional approach using a linear guide rail. The singularity of the mechanism is analyzed, and the design has been improved to avoid reaching singular positions. The master arm platform has been fabricated and assembled, and it possesses a large workspace of $300 \times 300 \times 173.2$ mm3. Both simulation and experiments have been performed to validate its effectiveness and advantages, and the proposed design can be applied as a generalized master platform to target NOTES surgery.

Sulfate erosion of concrete is a kind of salt erosion which causes great harm to materials. It is also one of the important factors affecting the degradation of carbon fiber reinforced polymer (CFRP)-concrete interface. In this study, the sulfate environment was simulated by the sulfate dry-wet cycle accelerated erosion test. The bonding properties of CFRP-concrete interface under the dry and wet cycle of sulfate were studied by using 18 double-sided shear specimens. The variation trend of interface failure characteristics and interface characteristic values (interfacial shear stress peak and its corresponding slip amount) with sulfate erosion time were analyzed, and the interface bond-slip relationship curves under different erosion times were obtained. Based on the statistical regression analysis of the experimental results, the relationship between the interface ductility parameters and the interface eigenvalues as a function of sulfate erosion time was obtained. Moreover, a bond-slip degradation model of CFRP-concrete interface under the action of sulfate dry-wet cycle was proposed. The model prediction curve agreed well with the experimental curve. Compared with the experimental data, the prediction model can better reflect the trend of the interface bond-slip curve and the degradation pattern of the interface bond performance with the time of sulfate dry-wet cycles.

Overhauser magnetometer, a kind of static-magnetic measurement system based on the Overhauser effect, has been widely used in archaeological exploration, mineral resources exploration, oil and gas basin structure detection, prediction of engineering exploration environment, earthquakes and volcanic eruotions, object magnetic measurement and underground buried booty exploration. Overhauser magnetometer plays an important role in the application of magnetic field measurement for its characteristics of small size, low power consumption and high sensitivity. This paper researches the design and the application of the analog circuit of JOM-3 Overhauser magnetometer. First, the Larmor signal output by the probe is very weak. In order to obtain the signal with high signal to noise rstio(SNR), the design of pre-amplifier circuit is the key to improve the quality of the system signal. Second, in this paper, the effectual step which could improve the frequency characters of bandpass filter amplifier circuit were put forward, and theoretical analysis was made for it. Third, the shaping circuit shapes the amplified sine signal into a square wave signal which is suitable for detecting the rising edge. Fourth, this design elaborated the optimized choice of tuning circuit, so the measurement range of the magnetic field can be covered. Last, integrated analog circuit testing system was formed to detect waveform of each module. By calculating the standard deviation, the sensitivity of the improved Overhauser magnetometer is 0.047nT for Earth’s magnetic field observation. Experimental results show that the new magnetometer is sensitive to earth field measurement.

Overhauser magnetometer is a detection instrument of the geomagnetic field. The sensitivity of Overhauser magnetometer is one of the important technical parameters. This paper introduces a high sensitivity and low power consumption JOM-2 Overhauser magnetometer based on Overhauser effect. A detailed description of the system controlled by DSP+CPLD is provided from three aspects: design principle, system composition and the sensitivity experimental test. In order to explore the sensitivity of JOM-2 under ideal and practical conditions, we give the test methods and results. Under ideal conditions, we use a DDS function signal generator to make a static magnetic field whose frequency and amplitude are constant and the signal to noise ratio (SNR) is high. And we use an analog function signal generator to generate a time-dependent magnetic field. These experimental results indicate that the ideal sensitivity of the JOM-2 Overhauser magnetometer is up to 0.003nT. Under practical conditions, the sensitivity can reach 0.043nT, which confirms that the JOM-2 Overhauser magnetometer is sensitive to geomagnetic field measurement.

The bond-slip performance and constitutive model of the interface between reinforcing steel bars and brick masonry are the basis for seismic performance analysis of reinforced masonry through finite element simulation. In this study, the gradual increase of the vertical load in masonry during construction is simulated using a convenient self-developed test setup that ensures that the specimen is under constant pressure based on the actual stress state of horizontal reinforcing steel bars in reinforced brick masonry. Both the vertical compressive stress and the bond length were considered as variables and were used to form 19 groups of specimens. The bond characteristics of reinforcing steel bars were investigated using pull-out tests. The bond-slip curves of the interface between the horizontal reinforcing steel bar and brick masonry were obtained from test data; then, a five-segment bond-slip model that considered the effect of the vertical compressive stress and the bond length on the bond performance is proposed. This study analysed the variation trend of the bond parameters of each feature point influencing the bond performance in the model. The initial bond stiffness of the micro-slip segment increased with the increase in the vertical compressive stress, and the ultimate bond stress increased significantly. The calculation formulas of the bonding parameters are obtained by regression statistics taking these factors into consideration. The predictions obtained from the model show good agreement with test results.

Overhauser proton magnetometer is a scalar instrument for measuring the total magnetic field intensity. Sensitivity, as one of the important specifications, reflects the ability to measure the change of magnetic field when detecting magnetic anomalies. It is very important to study the sensitivity estimation method for accurately evaluating the sensitivity specification of the magnetometer. In this paper, two methods, synchronous measurement method and gradient measurement method, are proposed to estimate the instrument sensitivity. The experimental results show that the lower the external environmental electromagnetic interference is, the more accurate the sensitivity estimation is. Furthermore, when the synchronization accuracy is about 1.7 milliseconds, the estimation results of the synchronization measurement method and the gradient measurement method are almost equal. Finally, in the environment with low electromagnetic interference, the sensitivity estimation of the JOM-4 magnetometers is 0.042 nT@3s.

To improve the disadvantage of the low reactivity and reduce the high curing temperature of epoxy resin cured by dicyandiamide (DICY), DICY is chemically modified with phenyl hydrazine and a new curing agent, LB-A, is developed in this research. The structure, the curing behavior, and reaction kinetics of LB-A curing epoxy resin are investigated. Results show that the DICY is modified successfully and the well-defined structure of DICY is destroyed after modification. Consequently, a new curing agent in a noncrystal form is resulted. Thereupon, the reactivity and compatibility between the epoxy resin and the curing agent are improved appreciably using LB-A instead of DICY. Meanwhile, the curing temperature and activation energy of the curing reaction decrease outstanding, whereas the rate constant increases remarkably. In addition, the compressive strength and the adhesive strength in shear by tension loading of the resulting epoxy resins have been increased using LB-A instead of DICY as the curing agent. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013