High Degree Of Freedom Research Articles

Robotic Anterior Resection for Rectosigmoid Colon Cancer using Single Port Access.

Single-port laparoscopic surgery (SPLS) and a robotic surgical system have recently been included in contemporary colorectal surgical practice. 1-4 SPLS may result in better cosmetic outcomes, reduced postoperative incisional pain, fewer incisional hernias, minimal organ damage, and fewer wound complications. 2,5 However, SPLS for left-sided colorectal cancer is a challenging technique, even for experienced laparoscopic colorectal surgeons, owing to the difficulty of constructing instrument triangulation and using endo-staplers in the pelvic cavity from a single umbilical port with adequate distal margins. The Da Vinci Si Single-Site ® system (Intuitive Surgical, Sunnyvale, CA) was specifically developed to overcome SPLS limitations. Since the robotic instruments are crossed at the port site, but the software "reassigns" them to the surgeon's hand on the robotic console, the platform can easily create instrument triangulation while minimizing external robotic arm collisions. 6-8 Due to the lack of wrist articulation, the limited range of motion of the semi-rigid robotic instruments, and the limited choice of instruments, the Single-Site ® platform has not yet been widely utilized for colorectal diseases. A novel robotic technique, the da Vinci SP ® system (Intuitive Surgical, Sunnyvale, CA, USA), was designed for single-site surgery. This platform has a robotic arm with a high degree of freedom that is introduced directly into the peritoneal cavity through a single incision. The benefits of the single-port da Vinci robot platform include a holographic display of the instrument location, wristed articulation and flexible elbows, a console-controlled camera, and three-dimensional optics. This robotic system for single-port access can perform lymph node dissection around the inferior mesenteric artery using 4-arm wrist articulation while preserving the autonomic nerves during left-sided colorectal cancer surgery.

Generalised two‐level nested multiple‐input multiple‐output radar direction of arrival estimation with high degrees of freedom and low mutual coupling

AbstractTo address the problems of traditional two‐level nested arrays (TTNA) with low degrees of freedom and high mutual coupling, a generalised two‐level nested MIMO radar array with high degrees of freedom and low mutual coupling for the direction of arrival (DOA) estimation is proposed. First, two coprime expansion factors are introduced in the TTNA to mitigate mutual coupling among array elements and enhance its degrees of freedom. Secondly, the range of consecutive lags and the total number of virtual array elements are derived in closed form under the structures of ‘sum–difference co‐array’. Finally, utilising the atomic norm minimisation theory, the authors address the issue of discrete holes caused by different coprime expansion factors through filling in virtual arrays at discontinuities. Furthermore, a convex optimisation model to recover equivalent received signals from these filled virtual arrays is established, which is combined with a multiple signal classification algorithm for DOA estimation. Simulation results validate the rationality of the array structure and demonstrate the effectiveness of the algorithm.

Generation of 3D quasi-spherical multi-focus arrays and optical rings using orthogonally superimposed dipole antenna arrays

This paper proposes a novel method to generate a three-dimensional (3D) quasi-spherical focal point with high longitudinal and transverse resolution in a 4Pi focusing system based on the radiation pattern of the orthogonally superimposed dipole antenna. In this paper, we present generated 3D quasi-spherical multi-focus arrays that are controllable and uniformly distributed and optical rings from the radiation patterns of antenna arrays in different configurations. The results showed that the generated focal point is smaller longitudinally (0.31λ) than transversely (0.41λ). This focal point has the smallest volume (∼0.0273λ 3) found. Moreover, it is highly homogeneous and has a small side lobe. The polarization at the center of the focal point is purely circular. The resulting 3D focal fields can be easily tailored by adjusting the modulation parameters of the orthogonally superimposed dipole arrays. Manipulating 3D optical focal fields with pre-defined characteristics of quasi-spherical focal points has a high degree of freedom. Many potential applications exist in arbitrarily oriented particle capture and guidance, micromanipulation, optical capture, and 3D optical data storage.

One-Pot Synthesis of Stable Poly([c2]Daisy–chain Rotaxane) with Pseudo-Stopper via Metathesis Reaction and Thiol-Ene Reaction

Rotaxanes, known as supramolecular compounds, are expected to find applications in functional materials due to their high degree of freedom. However, their synthesis requires multistep reactions, and there is a demand for more convenient methods to synthesize rotaxane materials. In this study, we aimed to investigate a simpler method for synthesizing highly functional rotaxane materials and explore the diversity of molecular designs. To achieve this, we successfully synthesized a host–guest conjugated compound that incorporates both crown ether as the host unit and secondary ammonium salts as the guest unit within the same molecule. Subsequently, the metathesis reaction of these compounds, which construct [c2]daisy-chain rotaxanes, enabled the one-pot synthesis of a topological polymer called “poly([c2]daisy-chain rotaxane)” with a pseudo-stopper. This methodology achieves the stabilization and polymerization of rotaxanes simultaneously, contributing to the easy materialization of rotaxanes. Furthermore, the thiol-ene reaction achieved the extension of the distance between rotaxane units and provided a useful approach to diversify the design of functional materials with rotaxane structures.

All-transparent tandem photovoltaic-powered photodetector

Can electronics operate independently and invisibly in designated places? If yes, the user would not recognize the existence of devices and this can be applied to various applications. The device should be optically transparent and simultaneously achieve transparent electric power to satisfy this invisible freedom. Herein, we propose a dual transparent platform consisting of a broad-range translucent photodetector powered by an invisible photovoltaic unit. Transparent photovoltaic (TPV) has a NiO/TiO2 heterojunction for high optical transparency of 79.7% and can produce a maximum voltage of 0.6 V at an efficiency of 13.4%. A transparent broadband photodetector (TBD) that comprises Co3O4/ZnO has high optical transparency (70%) and provides a broad wavelength photodetection. The TBD can be tuned in the reverse bias mode along with the separate power unit (TPV), which significantly enhances the responsivity to 6.8 mA W−1. In contrast to the self-powered operation mode, the dual system (TBD and TPV power units) can actively control the bias voltage to the TBD, supplied from the TPV (0–0.6 V). TPV and TBD have an overall transparency of 56.4% and long-term stability to allow a high degree of freedom in transparent human electronics, ensuring visional transparency and an independent power supply.

Automatic control method for freeform surface shapes.

Designing freeform optics with high degrees of freedom can improve their optical performances; however, there are high requirements for controlling the surface shapes of such optics. Optical designers need to add constraints to the optimization process and make repeated adjustments to ensure the manufacturability of these shapes; this process is cumbersome and relies heavily on the experience of the designer. In this study, an automatic control method for freeform surface shapes is proposed. By adding an outer loop to the optimization process, the principal curvature and sag departure of the sampling points are gradually controlled during the optimization cycle based on the system requirements and surface evaluation results. The method was implemented in CODE V and successfully applied to a design example in freeform prism optics.

Symmetry in a Fractional-Order Multi-Scroll Chaotic System Using the Extended Caputo Operator

In this work, complex dynamics are found in a fractional-order multi-scroll chaotic system based on the extended Gamma function. Firstly, the extended left and right Caputo fractional differential operators are introduced. Then, the basic features of the extended left Caputo fractional differential operator are outlined. The proposed operator is shown to have a new fractional parameter (higher degree of freedom) that increases the system’s ability to display more varieties of complex dynamics than the corresponding case of the Caputo fractional differential operator. Numerical results are performed to show the effectiveness of the proposed fractional operators. Then, rich complex dynamics are obtained such as coexisting one-scroll chaotic attractors, coexisting two-scroll chaotic attractors, or approximate periodic cycles, which are shown to persist in a shorter range as compared with the corresponding states of the integer-order counterpart of the multi-scroll system. The bifurcation diagrams, basin sets of attractions, and Lyapunov spectra are used to confirm the existence of the various scenarios of complex dynamics in the proposed systems.

Graphene-based metasurface for real-time control of three electromagnetic wave modes and polarization state

In various practical applications, the demand for switchable metasurfaces with versatile functionalities has grown significantly. This paper proposes a graphene-based metasurface that offers independent control over all three electromagnetic (EM) wave modes (i.e., reflection, transmission, and absorption) as well as the polarization state for both reflection and transmission modes, all achieved in real-time at terahertz frequency. The metasurface is designed with a multilayer structure, comprising quartz, gold, and graphene. Two graphene sheets are placed at the beginning and end of the structure to control specific functionalities. By dynamically adjusting the chemical potential of each graphene sheet, the proposed metasurface can manipulate all three EM wave modes and convert linear to circular polarization independently for both reflection and transmission modes. Additionally, the metasurface can switch from polarization conversion to without polarization conversion of the reflected wave by adjusting the chemical potential of graphene. Due to its numerous switchable functions and a high degree of freedom, the presented metasurface has the potential to be used in wireless communication, biomedicine, and optoelectronic devices.

Fast and Robust Non-Rigid Registration Using Accelerated Majorization-Minimization

Non-rigid 3D registration, which deforms a source 3D shape in a non-rigid way to align with a target 3D shape, is a classical problem in computer vision. Such problems can be challenging because of imperfect data (noise, outliers and partial overlap) and high degrees of freedom. Existing methods typically adopt the lp type robust norm to measure the alignment error and regularize the smoothness of deformation, and use a proximal algorithm to solve the resulting non-smooth optimization problem. However, the slow convergence of such algorithms limits their wide applications. In this paper, we propose a formulation for robust non-rigid registration based on a globally smooth robust norm for alignment and regularization, which can effectively handle outliers and partial overlaps. The problem is solved using the majorization-minimization algorithm, which reduces each iteration to a convex quadratic problem with a closed-form solution. We further apply Anderson acceleration to speed up the convergence of the solver, enabling the solver to run efficiently on devices with limited compute capability. Extensive experiments demonstrate the effectiveness of our method for non-rigid alignment between two shapes with outliers and partial overlaps, with quantitative evaluation showing that it outperforms state-of-the-art methods in terms of registration accuracy and computational speed. The source code is available at https://github.com/yaoyx689/AMM_NRR.

Exploration of Damage Identification Method for a Large-Span Timber Lattice Shell Structure in Taiyuan Botanical Garden based on Structural Health Monitoring.

Large-span spatial lattice structures generally have characteristics such as incomplete modal information, high modal density, and high degrees of freedom. To address the problem of misjudgment in the damage detection of large-span spatial structures caused by these characteristics, this paper proposed a damage identification method based on time series models. Firstly, the order of the autoregressive moving average (ARMA) model was selected based on the Akaike information criterion (AIC). Then, the long autoregressive method was used to estimate the parameters of the ARMA model and extract the residual sequence of the autocorrelation part of the model. Furthermore, principal component analysis (PCA) was introduced to reduce the dimensionality of the model while retaining the characteristic values. Finally, the Mahalanobis distance (MD) was used to construct the damage sensitive feature (DSF). The dome of Taiyuan Botanical Garden in China is one of the largest non-triangular timber lattice shells worldwide. Relying on the structural health monitoring (SHM) project of this structure, this paper verified the effectiveness of the damage identification model through numerical simulation and determined the damage degree of the dome structure through SHM measurement data. The results demonstrated that the proposed damage identification method can effectively identify the damage of large-span timber lattice structures, locate the damage position, and estimate the degree of damage. The constructed DSF had relatively strong robustness to small damage and environmental noise and has practical application value for SHM in engineering.

Antiresonant fiber structures based on swarm intelligence design.

In this work, we obtained a new, to the best of our knowledge, structure of anti-resonant fiber (ARF) by an adaptive particle swarm optimization (PSO) algorithm. Different from the prior method of stacking elemental parts and optimizing parameters through experience or algorithm, we decompose some classic structures into points and optimize the positions of these points through swarm intelligence. The fiber structure is reconstructed by interpolation, and some new structures with low confinement loss (CL) and high higher order mode extinction ratio (HOMER) are obtained. These novel ARFs exhibit similar structural characteristics, and are named as "the bulb-shaped ARFs". Among these structures, the minimum achieved CL is 2.21 × 10-5dB/m at 1300 nm and the maximum achieved HOMER exceeds 14,000. This work provides a method with high degree of freedom in the design of non-uniform cross-section waveguides and helps to discover new fiber structures.

An L-Shaped Three-Level and Single Common Element Sparse Sensor Array for 2-D DOA Estimation.

The degree of freedom (DOF) is an important performance metric for evaluating the design of a sparse array structure. Designing novel sparse arrays with higher degrees of freedom, while ensuring that the array structure can be mathematically represented, is a crucial research direction in the field of direction of arrival (DOA) estimation. In this paper, we propose a novel L-shaped sparse sensor array by adjusting the physical placement of the sensors in the sparse array. The proposed L-shaped sparse array consists of two sets of three-level and single-element sparse arrays (TSESAs), which estimate the azimuth and elevation angles, respectively, through one-dimensional (1-D) spatial spectrum search. Each TSESA is composed of a uniform linear subarray and two sparse subarrays, with one single common element in the two sparse subarrays. Compared to existing L-shaped sparse arrays, the proposed array achieves higher degrees of freedom, up to 4Q1Q2+8Q1-5, when estimating DOA using the received signal covariance. To facilitate the correct matching of azimuth and elevation angles, the cross-covariance between the two TSESA arrays is utilized for estimation. By comparing and analyzing performance parameters with commonly used L-shaped and other sparse arrays, it is found that the proposed L-shaped TSESA has higher degrees of freedom and array aperture, leading to improved two-dimensional (2-D) DOA estimation results. Finally, simulation experiments validate the excellent performance of the L-shaped TSESA in 2-D DOA estimation.

Manipulation of Spatial Infrared Emission Based on W‐Doped Vanadium Oxide Films toward Thermal Coding

AbstractActive thermal radiation control of an object requires adaptive and flexible strategies to cope with emissivity engineering and its temperature dependence. On the other hand, the concept of digital coding allows a high degree of freedom in manipulating the interacting physical quantities based on local discretized features. Learning from this idea, this study put forward the manipulation of spatial infrared emission based on tungsten (W)‐doped VO2 films toward thermal coding. Here, 1‐bit coding worksheets created by low‐emissivity, that is, code ‘0′, and high‐emissivity, that is, code ‘1′, shift with materials metal‐insulator phase transition to encode emissive information in the temperature domain. It is shown experimentally that this concept has marked implications on thermal radiation control at Mid‐infrared, among which are as follows: digital anti‐counterfeiting by in‐plane spatial coding of a group of VO2 thin films with various W‐doping density and infrared camouflage by out‐of‐plane spatial coding of them. With a W‐doping gradient of 0%, 0.8%, and 1.7%, the three‐phase transition points in the temperature domain, that is, 72, 63, and 45 °C, give a remarkable modulation range of 27 °C. These phenomena pave the way for new classes of emissivity engineering for more accurate, flexible, and adaptive thermal radiation control.

Improving Li percolation and redox reversibility of Li-rich disordered rocksalt cathode with Mn2+/4+ double redox via inactive d0 Nb5+ substitution

Disordered rocksalt (DRX) cathodes are promising for next-generation lithium-ion batteries due to its high discharge capacity. Benefiting from the high degree of freedom in compositional design, cationic multi-electron redox is realized through the stabilization of d0 transition metals (TMs), and irreversible oxygen loss is alleviated by increased TM capacity contribution. However, such materials reported so far are almost weakly crystalline (fluorine)oxides prepared by mechanochemical methods. Herein, we prepare highly crystalline Mn(II)-based DRX oxides Li1.15Mn0.275Ti0.575O2 (LMTO), and Li1.23Mn0.275Ti0.255Nb0.24O2 (LMTNO) with partial d0 Ti4+ replaced by d0 Nb5+. Increased lattice spacings of LMTNO are confirmed due to the larger ionic radius of Nb5+, which is conducive to Li+ diffusion. In combination with bond-valence sum method and electrochemical impedance spectroscopy, lower Li+ percolation energy and better rate performance of LMTNO are demonstrated kinetically. Density functional calculations reveal that d0 Nb5+ is superior to d0 Ti4+ for the stabilization of Mn-O bonds, and relieves MnO6 octahedral distortion to alleviate the Jahn-Teller effect. In-situ X-ray diffraction indicates that the structural evolution and redox reaction are more reversible in LMTNO during the electrochemical process. This work understands the effect of d0 TMs on the electrochemical performance of DRX cathodes and provides new insights into multi-electron redox.

Anisotropic programmable metasurface beam splitter based on diode real-time control

we propose an anisotropic programmable coding metasurface, which is composed of digital coding elements integrated with PIN diode. The "0″ and "1″ states of the diode are controlled in real time by external voltages, and a single metasurface unit is controlled by the FPGA (Field Programmable Gate Array). Due to the polarization-sensitive characteristics, it is not only possible to switch the polarization states in the orthogonal two directions separately, but also to realize the remote scattering control at any angle by means of convolution coding. The metasurface can be converted on polarization (linear polarization or circular polarization) by means of real-time coded modulation. We further experimentally prepared a diode based programmable coding metasurface and measured the angle of far-field scattering using a microwave test system. The independent polarization wavefront control greatly enhances the channel capacity of metasurface, and programmable metasurface has a higher degree of freedom when multifunction modulation is realized.

Multi-Agent Reinforcement Learning-Based Decentralized Controller for Battery Modular Multilevel Inverter Systems

The battery-based multilevel inverter has grown in popularity due to its ability to boost a system’s safety while increasing the effective battery life. Nevertheless, the system’s high degree of freedom, induced by a large number of switches, provides difficulties. In the past, central computation systems that needed extensive communication between the master and the slave module on each cell were presented as a solution for running such a system. However, because of the enormous number of slaves, the bus system created a bottleneck during operation. As an alternative to conventional multilevel inverter systems, which rely on a master–slave architecture for communication, decentralized controllers represent a feasible solution for communication capacity constraints. These controllers operate autonomously, depending on local measurements and decision-making. With this approach, it is possible to reduce the load on the bus system by approximately 90 percent and to enable a balanced state of charge throughout the system with an absolute maximum standard deviation of 1.1×10−5. This strategy results in a more reliable and versatile multilevel inverter system, while the load on the bus system is reduced and more precise switching instructions are enabled.

Experimental study on 3D printed heat pipes with hybrid screen–groove combined capillary wick structure

The integration of heat pipes as a passive thermal management system for nuclear reactors has been proposed as it provides the advantages of compact design, reliability, efficient heat transfer performance, and enhanced safety. Applying the heat pipe to a nuclear reactor without collision between systems and achieving efficient long-distance heat transfer requires the manufacturing of heat pipes with a high degree of freedom. Using three-dimensional (3D)-printing technology can be a solution for fabricating complex or bent capillary wick heat pipes into an integrated geometry. The study involves the production of a heat pipe using metal 3D-printing technology and an experimental study conducted for thermal performance evaluation. The heat pipe includes a combination of a screen-groove wick in the evaporator section, a groove wick in the adiabatic and condenser sections, and a bent wick structure in the middle. By using 3D printing technology, it is possible to create a heat pipe that has a complex wick design, a consistent porous structure and remains undistorted during the manufacturing process. The surface roughness of the 3D-printed heat pipe was 17 to 1700 times higher than the commercial stainless-steel pipe, which has the benefit for enhance capillary performance. The experimental results showed that the 3D-printed heat pipe can achieve high effective thermal conductivity up to 25.7 kW/m-K and showed 24.2% lower thermal resistance compared to the conventionally manufactured heat pipe. Furthermore, it can be successfully operated at various inclination angles.

The generalized nonlocal fractal calculus: an efficient tool for fractal circuit analysis

PurposeThe purpose of this paper is to propose a novel nonlocal fractal calculus scheme dedicated to the analysis of fractal electrical circuit, namely, the generalized nonlocal fractal calculus.Design/methodology/approachFor being generalized, an arbitrary kernel function has been adopted. The condition on order has been derived so that it is not related to the γ-dimension of the fractal set. The fractal Laplace transforms of our operators have been derived.FindingsUnlike the traditional power law kernel-based nonlocal fractal calculus operators, ours are generalized, consistent with the local fractal derivative and use higher degree of freedom. As intended, the proposed nonlocal fractal calculus is applicable to any kind of fractal electrical circuit. Thus, it has been found to be a more efficient tool for the fractal electrical circuit analysis than any previous fractal set dedicated calculus scheme.Originality/valueA fractal calculus scheme that is more efficient for the fractal electrical circuit analysis than any previous ones has been proposed in this work.

Underdetermined direction of arrival estimation with nonuniform linear motion sampling based on a small unmanned aerial vehicle platform

Uniform linear array (ULA) radars are widely used in the collision-avoidance radar systems of small unmanned aerial vehicles (UAVs). In practice, a ULA’s multi-target direction of arrival (DOA) estimation performance suffers from significant performance degradation owing to the limited number of physical elements. To improve the underdetermined DOA estimation performance of a ULA radar mounted on a small UAV platform, we propose a nonuniform linear motion sampling underdetermined DOA estimation method. Using the motion of the UAV platform, the echo signal is sampled at different positions. Then, according to the concept of difference co-array, a virtual ULA with multiple array elements and a large aperture is synthesized to increase the degrees of freedom (DOFs). Through position analysis of the original and motion arrays, we propose a nonuniform linear motion sampling method based on ULA for determining the optimal DOFs. Under the condition of no increase in the aperture of the physical array, the proposed method obtains a high DOF with fewer sampling runs and greatly improves the underdetermined DOA estimation performance of ULA. The results of numerical simulations conducted herein verify the superior performance of the proposed method.

Application of Noncircular Pulleys to Straight-Fiber-Type Pneumatic Artificial Muscle Manipulator

This study proposes a method for improving the performance of a manipulator driven by pneumatic artificial muscles. Although the straight-fiber-type pneumatic artificial muscle (SF-PAM), a kind of pneumatic artificial muscle, is lightweight and exhibits high contractile force and contraction percentage, its contractile force decreases as contraction increases. To compensate for the decrease in the SF-PAM contractile force, we developed a noncircular pulley and integrated it into the manipulator driven by a wire pulley mechanism. Because this noncircular pulley is designed in accordance with the output characteristics of SF-PAM, the contraction force of SF-PAM can be converted into manipulator torque efficiently. In addition, the radius of the noncircular pulley is expressed as a function, which can be incorporated into a numerical model for the manipulator’s controller. Subsequently, simulation and experimentation to verify the proposed method showed that, when using the same actuator, the manipulator with a noncircular pulley can optimize both output torque and range of motion better than that with a conventional circular pulley. However, a few differences between simulation results and experimental results were observed. These differences were caused by SF-PAM stretching which was not considered in the model. This drawback can be overcome by improving the SF-PAM and the numerical model in future studies. We believe that this study will provide designers of robots that coexist with humans with a high degree of freedom.