Design and dynamic analysis of a scissors hoop-rib truss deployable antenna mechanism

As the support mechanism of space-borne antennas,space deployable antenna mechanism belongs to complex multi-closed-loop coupling mechanism,configuration design and dynamic analysis are more difficult than general parallel mechanism.In this paper,an unequal-length scissors mechanism(ULSM)is proposed by changing the position of the internal rotational joint through a basic scissors mechanism.A scissors hoop-rib truss deployable antenna mechanism(SHRTDAM)is constructed by replacing the parabolic rib with the ULSM.Kinematic analysis of SHRTDAM is conducted,and the degree of freedom(DOF)of the whole antenna mechanism is analyzed based on screw theory,the result showed that it has only one DOF.Velocity and acceleration characteristics of SHRTDAM are obtained by the screw derivative and rotation transformation.Based on Lagrange equation,dynamic model of this mechanism is established,the torque required to drive the mechanism is simulated and verified by Adams and MATLAB software.In addition,a ground experiment prototype of 1.5-m diameter was fabricated and a deployment test is conducted,which demonstrated the mobility and deployment performance of the whole mechanism.The mechanism proposed in this paper can provide a good reference for the design and analysis of large aperture space deployable antennas.

Quantum properties of nonclassical states generated by an optomechanical system with catalytic quantum scissors

A scheme is proposed to investigate the non-classical states generated by a quantum scissors device(QSD) operating on the the cavity mode of an optomechanical system. When the catalytic QSD acts on the cavity mode of the optomechanical system, the resulting state contains only the vacuum, single-photon and two-photon states depending upon the coupling parameter of the optomechanical system as well as the transmission coefficients of beam splitters(BSs). Especially, the output state is just a class of multicomponent cat state truncations at time t = 2π by choosing the appropriate value of coupling parameter. We discuss the success probability of such a state and the fidelity between the output state and input state via QSD. Then the linear entropy is used to investigate the entanglement between the two subsystems, finding that QSD operation can enhance their entanglement degree. Furthermore, we also derive the analytical expression of the Wigner function(WF) for the cavity mode via QSD and numerically analyze the WF distribution in phase space at time t =2π. These results show that the high non-classicality of output state can always be achieved by modulating the coupling parameter of the optomechanical system as well as the transmittance of BSs.

A new breakthrough:ESD using a newly developed grasping type scissor forceps for early gastrointestinal tract neoplasms

Endoscopic submucosal dissection(ESD) has allowed the achievement of histologically curative en bloc resection of gastrointestinal neoplasms regardless of size,permitting the resection of previously non-resectable tumors.The ESD technique for treatment of early gastric cancer has spread rapidly in Japan and a few other Asian countries due to its excellent eradication rate compared to endoscopic mucosal resection.Although numerous electrosurgical knives have been developed for ESD,technical difficulties and high complication rates(bleeding and perforation) have limited their use worldwide.We developed the grasping type scissor forceps(GSF) to resolve such ESD-related problems.Our animal and preliminary clinical studies showed that ESD using GSF is a safe(no intraoperative complication) and technically efficient(curative en bloc resection rate 92%) method for dissection of early gastrointestinal tumors.The use of GSF is a promising option for performing ESD on early stage GI tract tumors both safely and effectively.

Kinematics and Dynamics of Deployable Structures with Scissor-Like-Elements Based on Screw Theory

Because the deployable structures are complex multi-loop structures and methods of derivation which lead to simpler kinematic and dynamic equations of motion are the subject of research effort, the kinematics and dynamics of deployable structures with scissor-like-elements are presented based on screw theory and the principle of virtual work respectively. According to the geometric characteristic of the deployable structure examined, the basic structural unit is the common scissor-like-element（SLE）. First, a spatial deployable structure, comprised of three SLEs, is defined, and the constraint topology graph is obtained. The equations of motion are then derived based on screw theory and the geometric nature of scissor elements. Second, to develop the dynamics of the whole deployable structure, the local coordinates of the SLEs and the Jacobian matrices of the center of mass of the deployable structure are derived. Then, the equivalent forces are assembled and added in the equations of motion based on the principle of virtual work. Finally, dynamic behavior and unfolded process of the deployable structure are simulated. Its figures of velocity, acceleration and input torque are obtained based on the simulate results. Screw theory not only provides an efficient solution formulation and theory guidance for complex multi-closed loop deployable structures, but also extends the method to solve dynamics of deployable structures. As an efficient mathematical tool, the simper equations of motion are derived based on screw theory.

Novel Surface Design of Deployable Reflector Antenna Based on Polar Scissor Structures

Space-deployable mechanisms can be used as supporting structures for large-diameter antennas in space engineering.This study proposes a novel method for constructing the surface design of space reflector antennas based on polar scissor units.The concurrency and deployability equations of the space scissor unit with definite surface constraints are derived using the rod and vector methods.Constraint equations of the spatial transformation for space n-edge polar scissor units are summarized.A new closed-loop deployable structure,called the polar scissor deployable antenna(PSDA),is designed by combining planar polar scissor units with spatial polar scissor units.The overconstrained problem is solved by releasing the curve constraint that locates at the end-point of the planar scissor mechanism.Kinematics simulation and error analysis are performed.The results show that the PSDA can effectively fit the paraboloid of revolution.Finally,deployment experiments verify the validity and feasibility of the proposed design method,which provides a new idea for the construction of large space-reflector antennas.

Numerical Calculations of Aerodynamic and Acoustic Characteristics for Scissor Tail-Rotor in Forward Flight

The aerodynamic and aeroacoustic characteristics of a scissor tail-rotor in a forward flight are numerically calculated.A novel computational fluid dynamics(CFD)model based on Navier-Stokes(N-S)equations is presented to simulate the unsteady flowfield and the aerodynamic characteristics of a scissor tail-rotor in the forward flight.Then the Farassat Formulation 1 Aderived from the FW-H equation is coupled into the CFD model in order to compute the aeroacoustic characteristics of the scissor tail-rotor.In addition,two different scissor tail-rotor configurations,i.e.,the L-and U-configuration,are analyzed in details and compared with a conventional one.The influence of scissor angles on the aerodynamic and aeroacoustic characteristics of the scissor tail-rotor is also investigated.The simulation results demonstrate that the flowfield,aerodynamic force and aeroacoustic characteristics of a scissor tail-rotor are significantly different from the conventional one,and the aerodynamic interaction decreases with the increase of scissor angle,which leads to a reduction of amplitude variation of the tail-rotor thrust in the forward flight.The scissor angle has an important effect on the aerodynamics and aeroacoustics of the scissor tail-rotor.

A New Flexible Multibody Dynamics Analysis Methodology of Deployable Structures with Scissor-Like Elements

There are vast constraint equations in conventional dynamics analysis of deployable structures,which lead to differential-algebraic equations(DAEs)solved hard.To reduce the difficulty of solving and the amount of equations,a new flexible multibody dynamics analysis methodology of deployable structures with scissor-like elements(SLEs)is presented.Firstly,a precise model of a flexible bar of SLE is established by the higher order shear deformable beam element based on the absolute nodal coordinate formulation(ANCF),and the master/slave freedom method is used to obtain the dynamics equations of SLEs without constraint equations.Secondly,according to features of deployable structures,the specification matrix method(SMM)is proposed to eliminate the constraint equations among SLEs in the frame of ANCF.With this method,the inner and the boundary nodal coordinates of element characteristic matrices can be separated simply and efficiently,especially on condition that there are vast nodal coordinates.So the element characteristic matrices can be added end to end circularly.Thus,the dynamic model of deployable structure reduces dimension and can be assembled without any constraint equation.Next,a new iteration procedure for the generalized-a algorithm is presented to solve the ordinary differential equations(ODEs)of deployable structure.Finally,the proposed methodology is used to analyze the flexible multi-body dynamics of a planar linear array deployable structure based on three scissor-like elements.The simulation results show that flexibility has a significant influence on the deployment motion of the deployable structure.The proposed methodology indeed reduce the difficulty of solving and the amount of equations by eliminating redundant degrees of freedom and the constraint equations in scissor-like elements and among scissor-like elements.

Late Precambrian Scissors--Type Opening--Closing Tectonics and Its Dynamics in South China

In this paper the author first reviews 6 major advances in the study of Precambrian geologyand tectonics of South China during the last decade, and then proposes the following new modelof Late Precambrian scissors-type opening-closing tectonic evolution in the region. (1) Besidesthe Middle-Late Proterozoic low-grade metamorphic basement, there existed a LateArchaean-Early Proterozoic medium- to high-garde metamorphic basement in South China;both of them formed the united Yangtze-Cathaysia (craton) at the end of the Early Proterozoic,with the Jiangxi-Anhui-Zhejiang palaeogulf extending into the inland and the Jiangxi-Anhui-Jiangsu Peninsula lying on the northern side of the palaeogulf.(2) From the Middle Proterozoic,the present Guangxi-Guizhou-Hunan area in the western-central oldland was subjected toextensional rifting and became a rift trough, thus resulting in counterclockwise rotation of the'Cathaysian block' and clockwise rotation of the 'Yangtze block'; moreover, the southwardcompression of the Dabie-Jiaonan block which split from the southern margin of the NorthChina plate and was accreted to the northern margin of the Jiangxi-Anhui-Jiangsu Peninsula ledto the scissors-type closing of the Jiangxi-Anhui-Zhejiang palaeogulf during the Middle-earlyLate Proterozoic, which further influenced the Early Palaeozoic tectonic evolution of the region.

Grasper type scissors for endoscopic submucosal dissection of gastric epithelial neoplasia

AIM:To evaluate the efficacy and safety of grasper type scissors(GTS)for endoscopic submucosal dissection(ESD)of gastric epithelial neoplasia.METHODS:The study was performed by 4 endoscopists in 4 institutions affiliated to The Catholic University of Korea.ESD was performed in 76 consecutive patients with gastric epithelial neoplasia by using the GTS(37 patients)or the hook knife plus coagrasper(HKC)(39 patients).The complete resection rate,complication rate,total time elapsed and elapsed time per square centimeter of the dissected specimen were analyzed between the GTS and HKC group.RESULTS:The mean age of the GTS group was 62.3±11.4 years and mean age of the HKC group was 65.6±10.1 years.Differentiated adenocarcinoma was found in32.4%in the GTS group and 33.3%in the HKC group.The procedures were performed without interruption in every case in both groups.The en bloc resection rates of both groups were 100%.The total time elapsed during the procedure was 44.54±21.72 min in the GTS group and 43.77±21.84 min in the HKC group(P=0.88)and the time elapsed per square centimeter of the resected lesion was 7.53±6.35 min/cm2in the GTS group and 6.92±5.93 min/cm2in the HKC group(P=0.66).The overall complication rate was not significantly different between the two groups.CONCLUSION:GTS is a safe and effective device for ESD compared with HKC.ESD can be performed with GTS alone,which can reduce the costs for ESD.

Simulation on Helicopter Scissors Tail-Rotor Noise Based on N-S Equations and F1A Formulas

Aiming at the noise of helicopter scissors tail-rotor,an advanced numerical method is established by combining computational fluid dynamics(CFD)model with Farassat 1 A(F1 A)formula.In this method,Navier-tokes(N-S)equations are used as governing equations,and the flow field is solved at quasi-steady and unsteady states in hover and forward fight,respectively,based on two different types of embedded grid systems.A simple and effective solution approach is provided for the generation difficulty of donor cells caused by the close gap among scissors tail-rotor blades.Using the CFD calculation results as input,the thickness noise,loading noise and total noise of tail-rotor are calculated by F1 Aformula.By the method,numerical examples on rotor flowfield and noise are performed and the results are compared with available data.Then,aerodynamic and acoustic characteristics of scissors tail-rotor are emphatically calculated in both hover and forward flight.Furthermore,the research on the effects of blade-tip shape parameters on scissors tail-rotor noise is carried out.Also,the scissors tail-rotor is compared with the conventional tail-rotor,and the results show that in hover,the noise of a scissors tail-rotor is not always the smaller one.

Improvement of a continuous-variable measurement-device-independent quantum key distribution system via quantum scissors

We propose a new scheme to enhance the performance of the Gussian-modulated coherent-state continuous-variable measurement-device-independent quantum key distribution(CV-MDI-QKD)system via quantum scissors(QS)operation at Bob's side.As an non-deterministic amplifying setup,we firstly introduce the QS-enhanced CV-MDI-QKD protocol and then investigate the success probability of the QS operation in accordance with the equivalent one-way scheme.Afterwards,we investigate the effect of the QS operation on the proposed scheme and analyze the performance of the QS-enhanced CV-MDI-QKD system under the extreme asymmetric circumstance.Simulation results show that the QS operation can indeed improve the performance of the CV-MDI-QKD system considerably.QS-enhanced CV-MDI-QKD protocol outperforms the original CV-MDI-QKD protocol in both the maximum transmission distance and the secret key rate.Moreover,the better the performance of QS operation,the more significant the improvement of performance of the system.

Statistics of states generated by quantum-scissors device

Generating desired states is a prerequisite in quantum information. Some desired states can be generated by a quantum-scissors device(QSD). We present a detailed analysis of the properties of the generated states, including average photon numbers and intensity gains. The theoretical analysis shows that there is a nondeterministic amplification in terms of the average photon number under the condition that the average photon number of the input state is less than 1. In contrast to the input states, the generated states show the nonclassical property described by the negativity of the Wigner function. Furthermore, we generalize the QSD to truncate arbitrary photon number terms of the input states, which may be useful in high-dimensional quantum information processing.

Advances in endoscopic therapy using grasping-type scissors forceps(with video)

Endoscopic submucosal dissection(ESD)is a globally accepted minimally invasive therapy for early-stage gastrointestinal tract tumors.Although numerous electrosurgical knives have been developed for ESD,technical difficulties and high complication rates(bleeding and perforation)have limited their use worldwide.The grasping-type scissors forceps[clutch cutter(CC)]is the first forceps-type resection device developed with reference to hemostatic forceps.The aim was to allow easy and safe ESD throughout the gastro-intestinal tract,as a biopsy technique,using one device.The CC can grasp the target tissue accurately and pull it away from the underlying muscle layer prior to energizing the tissue,for safe and effective incision and hemostasis during ESD.Reported clinical studies showed that ESD using the CC(ESD-CC)is a safe(perforation rate:0%-3.6%;delayed bleeding rate:0%-4.2%),technically efficient(en-bloc resection rate:88.9%-100%),and single-device method for dissecting early-stage gastrointestinal tract tumors.The ESD-CC technique is simple and easy to learn because it can be completed simply by repeating the grasp,pull,and coagulate and/or incise actions using an electrosurgical current.The reported self-completion rate by nonexperts was significantly better with the CC than with conventional knives(61.7%vs 24.5%,respectively;P<0.001).Furthermore,the CC is used for other endoscopic therapies,such as endoscopic polypectomy for large pedunculated polyps,endoscopic myotomy for Zenker’s diverticulum,endoscopic treatment of buried bumper syndrome,and endoscopic necrosectomy for wall-off pancreatic necrosis.The initial reports using CC for these therapies have shown favorable results.In this review,we describe the structural features of the CC,how to use the instrument,efficacies of ESD-CC,and other unique endoscopic therapies using the CC.

Harmonic scalpel versus traditional scissors in laparoscopic partial nephrectomy:A propensity score-based analysis

Objective:The present study aims to compare the clinical efficacy of laparoscopic partial nephrectomy using a harmonic scalpel versus traditional scissor.Methods:A retrospective review was conducted in patients with localized renal tumors and scheduled for laparoscopic partial nephrectomy from January 2015 to December 2019.Eventually,225 patients joined this retrospective study.Patients were divided into the harmonic scalpel group or scissor group based on the method used,with 71 cases and 154 cases respectively.Propensity score matching(1:1)was performed to adjust for potential baseline confounders,and each group had 57 cases.Patient characteristics,perioperative clinical results,complications,and oncological results were compared between the two groups.Results:After matching,patient characteristics were not significantly different between the two groups.The scissor group was associated with a significantly shorter operative time(105 min vs.130 min,p<0.001),shorter warm ischemia time(19.35 min vs.22.07 min,p?0.005).However,the harmonic scalpel group was associated with significantly less estimated blood loss(20 mL vs.30 mL,p?0.013)and shorter length of stay(8 d vs.10 d,p?0.040).There was no significantly difference in indwelling time of drainage tube,perioperative complication,oncological outcomes or recurrence rates.Conclusions:The harmonic scalpel is used safely and effectively in laparoscopic partial nephrectomy,and has benefits in intraoperative blood loss and length of stay.

Age-Old Chinese Scissors

The production of scissors in China can be traced back about 4000 years. In ancient times, Chinese people called scissors "cutters" or "reamers". The cutters unearthed from an ancient tomb of the Western Han Dynasty (206B.C. —— 8 A.D.) in Luoyang of Henan Province were made in the shape of the figure "8" with an opening at its top and without any pivot. They were bent into shape with an iron bar blade at both ends.

Endoscopic submucosal dissection of a rectal carcinoid tumor using grasping type scissors forceps

Endoscopic submucosal dissection (ESD) with a knife is a technically demanding procedure associated with a high complication rate. The shortcomings of this method are the inability to fix the knife to the target lesion, and compression of the lesion. These can lead to major complications such as perforation and bleeding. To reduce the risk of complications related to ESD, we developed a new grasping type scissors forceps (GSF), which can grasp and incise the targeted tissue using electrosurgical current. Colonoscopy on a 55-year-old woman revealed a 10-mm rectal submucosal nodule. The histological diagnosis of the specimen obtained by biopsy was carcinoid tumor. Endoscopic ultrasonography demonstrated a hypoechoic solid tumor limited to the submucosa without lymph node involvement. It was safely and accurately resected without unexpected incision by ESD using a GSF. No delayed hemorrhage or perforation occurred. Histological examination confirmed the carcinoid tumor was completely excised with negative resection margin.

SCISSORS DIFFERENCE AND ITS IMPACTS ON ECONOMIC VALUE OF CULTIVATED LAND IN CHINA

The problem of price scissors difference between industrial products and agricultural products is one of the important problems in China. It impacts not only the living standard improvement of farmers but also the economic value of cultivated land, furthermore results in the direct and indirect loss of cultivated land resources. China’s cultivated land area has decreased dramatically in recent years. An important reason for the decrease is the relatively low cost of cultivated land occupancy, which results from the distortion of economic value of cultivated land due to the existence of scissors difference. This study firstly analyzed the dynamic change of scissors difference and calculated the absolute and relative magnitude of scissors difference from 1997 to 2002, then computed the economic value of cultivated land before and after scissors difference adjustment in 2002, and finally discussed the inverted scissors difference. Results suggest that the scissors difference has a remarkable impact on the economic value of cultivated land, and the adjustment of scissors difference even inverted scissors difference to the economic value of cultivated land is indispensable.

An Analysis of the Kinetic Features of Scissor Elevator Mechanism and Its Optimized Design

A mathematical model has been established for the research on scissor elevator for ship passenger stairs.The kinematical and kinetic simulation analyses were carried out with MATLAB/Simulink.The relative kinetic relation between hydraulic cylinder and other parts,as well as its rules of change has been found.A 3-D model of ship scissor elevator was established with Pro/E.The design of the mechanism was optimized in Pro/MECHANICA based on the findings from simulation analysis.Practice has proved that the design is scientific and reasonable and could serve as the theoretical guidance and reference for the design of scissor mechanism of other uses.

A portable,auxiliary photovoltaic power system for electric vehicles based on a foldable scissors mechanism

In recent years,countries worldwide have actively advocated electric vehicles for environmental protection.How-ever,restrictions on the driving range and charging have hampered the promotion of electric vehicles.This study proposes a portable,auxiliary photovoltaic power system based on a foldable scissors mechanism for electric vehicles.The system includes a photovoltaic power generation module and an electricity transfer module.The photovoltaic power generation module built based on a foldable scissors mechanism is five times smaller than in its unfolded state,improving its portability in its folded state.The electricity transfer module transfers electricity into the cabin via wireless power transfer units and stores electricity in supercapacitors.Solar simulation exper-iments were conducted to evaluate the system’s performance:maximum output power of 1.736 W is measured when the load is 5Ω,while maximum wireless power transfer efficiency is up to 57.7% with 10Ω load.An elec-tric vehicle in Chengdu city was simulated for a case study.The results show that the annual output of a single photovoltaic power system can drive the MINIEV for 423.625 km,indicating that the proposed system would be able to supply power for electric vehicles as an auxiliary power supply system.

具有变泊松运动特性的剪叉式折展机构运动学分析

为提高折展机构的折展率和支撑性能,提出了一种具有变泊松运动特性的剪叉式折展机构并对其进行运动学分析。首先,提出了一种单闭环厚板支撑单元并将其应用于三明治结构,利用ANSYS Workbench软件分析不同形状夹芯层对三明治结构支撑刚度的影响,发现采用厚板支撑单元的三明治结构具有更好的支撑效果和更小的质量,且可通过改变结构设计参数来实现正负泊松比的切换。然后,根据泊松比的定义,设计了一种具有变泊松运动特性的正n边形剪叉式折展机构;基于螺旋理论,通过绘制闭环折展机构的旋量约束拓扑图分析得到其自由度为1,将折展机构分为3种模块并阐述了模块化纵向扩展的原理和过程。最后,建立了m层正n边形剪叉式折展机构的运动学模型并搭建了正四边形剪叉式折展支撑结构实物样机,进一步验证了机构的变泊松运动特性,这可为后续的研究提供理论基础。