PERFORMANCE OF A KIND OF PERMANENT MAGNETICSUCKERSUSED IN WALL- CLIMBING ROBOTS

The magnetic circuit of a kind of permanent magnetic sucker attached to the tracks of a wall climbing robot was researched. The formula of the attractive force of sucker to a wall was derived and the relationship between the force and the air gaps was analyzed. Furthermore the effect of the parameters of the magnetic sucker on the sucker’s performance was discussed. The experiments show that proper selections of the sucker’s structural parameters can provide sufficient attractive force so as to make the wall climbing robot move safely on the steel wall surface.

浅谈窑制铸造玻璃的Suckers现象

窑制铸造玻璃的Suckers现象具有普遍性，这种现象影响着玻璃作品的成型。作者试图通过呈现窑制铸造玻璃Suckers现状，结合已完成的实验数据和已掌握的理论知识，进行初步的原因分析，根据其分析结论提出目前可行的解决办法，减少玻璃窑制铸造中Suckers的产生几率，从而提高玻璃窑制铸造的技术。本文意在引出该课题，希望更多从事玻璃艺术的群体关注该课题，运用科学的方法进行探索研究，总结出相应的解决办法，避免玻璃窑制铸造中Suckers的产生，促使该技术更好地服务于玻璃艺术创作。

Development of Biomimetic Squid-Inspired Suckers

Biomechanical properties of squid suckers were studied to provide inspiration for the development of sucker artefacts for a robotic octopus. Mechanical support of the rings found inside squid suckers was studied by bending tests. Tensile tests were carried out to study the maximum possible sucking force produced by squid suckers based on the strength of sucker stalks, normalized by the sucking areas. The squid suckers were also directly tested to obtain sucking forces by a special testing ar- rangement. Inspired by the squid suckers, three types of sucker artefacts were developed for the arm skin of an octopus inspired robot. The first sucker artefact made of knitted nylon sheet reinforced silicone rubber has the same shape as the squid suckers. Like real squid suckers, this type of artefact also has a stalk that is connected to the arm skin and a ring to give radial support. The second design is a straight cylindrical structure with uniform wall thickness made of silicone rubber. One end of the cylinder is directly connected to the arm skin and the other end is open. The final design of the sucker has a cylindrical base and a concave meniscus top. The meniscus was formed naturally using the surface tension of silicone gel, which leads to a higher level of the liquid around the edge of a container. The wall thickness decreases towards the tip of the sucker opening. Sucking forces of all three types of sucker artefacts were measured. Advantages and disadvantages of each sucker type were discussed. The final design of suckers has been implemented to the arm skin prototypes.

Mechanical characteristic and failure mechanism of joint with composite sucker rod

Composite sucker rods are widely used in oil fields because of light weight,high strength,and corrosion resistance.Bonded technology becomes the primary connection method of composites.However,the joints with composite sucker rods are prone to debone and fracture.The connected characteristics are less considered,so the failure mechanism of the joint is still unclear.Based on the cohesive zone model(CZM)and the Johnson-Cook constitutive model,a novel full-scale numerical model of the joint with composite sucker rod was established,and verified by pull-out experiments.The mechanical properties and slip characteristics of the joint were studied,and the damaged procession of the joint was explored.The results showed that:a)the numerical model was in good agreement with the experimental results,and the error is within 5%;b)the von Mises stress,shear stress,and interface stress distributed symmetrically along the circumferential path increased gradually from the fixed end to the loading end;c)the first-bonded interface near the loading end was damaged at first,followed by debonding of the second-bonded interface,leading to the complete shear fracture of the epoxy,and resulted in the debonding of the joint with composite sucker rod,which can provide a theoretical basis for the structural design and optimization of the joint.

Embryonic development of the concave-eared torrent frog with its significance on taxonomy

We investigated the early embryonic and larval development of the concave-eared torrent frogs, Odorrana tormota （Amphibia, Anura, Ranidae）. Embryos were derived from artificial fertilization of frogs’ eggs, and the staging of development was based on morphological and physiological characteristics. Two major periods of development were designated： i） early embryonic period, from fertilization to operculum completion stage, lasted for 324 h at water temperature （WT） 18 ？23℃; ii） larval period, from operculum completion stage to tail absorbed stage, took 1207 h at WT 20 ？ 24℃. Tadpoles of the concave-eared torrent frogs showed no evidence of abdominal sucker. Absence of this key characteristic supports the view from molecular systematics that concave-eared torrent frog does not belong to the genus Amolops. Two cleavage patterns were observed in embryos at 8-cell and 16-cell stages, with Pattern I2 （latitudinal cleavage at the 8-cell stage, and meridional cleavage at the 16-cell stage with two perpendicular meridional furrows） being the predominant pattern and only 1.5% belonging to Pattern II （meridional cleavage at the 8-cell stage and latitudinal cleavage at the 16-cell stage）. The factors affecting cleavage and hatching ratios, developmental speed, and ecological adaptation were discussed.

Ultrastructural Changes of Scolex on Cysticercus pisiformis during Relative Rest and Motion States

[Objective] This study aimed to research the ultra-morphological changes of scolex of Cysticercus pisiformis during the relative rest and motion states. [Method] The ultrastructure changes of scolex located in cyst and evaginated from cyst after cultivation were comparatively observed by scanning electron microscope. [Result] When the scolex was in the relative rest state, observed from the top, the rostel um with the tegument muscular column that connected to tooth-hook looked like the umbrel a and covered on the front end of the scolex. Viewed from the side of the scolex, the tooth-hook on the rostel um looked like the antler branch and had only one row. Four suckers looked like cavities, and were located in the back of the rostel um and distributed around the scolex in the equidistance. When the scolex was in the motion states, the tegument muscular column on the rostel um contracted, the antler-like tooth-hook extended to periphery, and the sucker also made the ring-like and longitudinal-like contraction. [Conclusion] Ultrastructure of the scolex of C. pisiformis changed apparently during relative rest and motion states. Those changes help scolex to invade the host tissue.

THE STUDY OF EARLY DEVELOPMENT AND EVOLUTION OF Torrentophryne aspinia

Torrentophryne aspinia is a new kind of toads discovered in China recently, it lives in the forest floor in West Yunnan, the most important things for this kind of species is that they have a kind of torrent-adapted tadpoles which have abdominal suckers and can adhere to the surfaces of rocks in moving waters. In this article, we described the forming procedures of abdominal sucker and some breeding behaviors, habitats and habits. After comparing with those of other toads, it is confirmed that Torrentophryne should be a new valid genus, it is derived from ancestor toads because of adaptation to the torrent habitats, by the forming of torrent -adapted organ-abdominal sucker in the early development.

A Method for Forecasting Failures of Sucker Rod-pumped Wells

An exact forecast of the failures of a sucker rod-pumped well in a production area means much for an oilfield’s operation budget, operational arrangement and production plan. In this paper, according to the characteristics of failed sucker rod-pumped well randomness and strong outburst, with the gray GM (1,1) forecast model and the Markov forecast model combined, gray GM (1,1) forecast model is utilized to handle the primary data of an oilfield, and Markov forecast model is utilized to calculate the state transfer probability of forecast value. Then, the gray Markov forecast model considering the influence of randomness factors is formed. Field results prove that the calculation precision of this method is higher and the practicability is greater.

Using the curve moment and the PSO-SVM method to diagnose downhole conditions of a sucker rod pumping unit

Downhole working conditions of sucker rod pumping wells are automatically identified on a computer from the analysis of dynamometer cards. In this process, extraction of feature parameters and pattern classification are two key steps. The dynamometer card is firstly divided into four parts which include different production information according to the ＂four point method＂ used in actual oilfield production, and then the moment invariants for pattern recognition are extracted. An improved support vector machine （SVM） method is used for pattern classification whose error penalty parameter C and kernel function parameter g are optimally chosen by the particle swarm optimization （PSO） algorithm. The simulation results show the method proposed in this paper has good classification results.

Fault diagnosis for down-hole conditions of sucker rod pumping systems based on the FBH-SC method

Dynamometer cards are commonly used to analyze down-hole working conditions of pumping systems in actual oil production. Nowadays, the traditional supervised learning methods heavily rely on the classification accuracy of the training samples. In order to reduce the errors of manual classification, an automatic clustering algorithm is proposed and applied to diagnose down-hole conditions of pumping systems. The spectral clustering （SC） is a new clustering algorithm, which is suitable for any data distribution. However, it is sensitive to initial cluster centers and scale parameters, and needs to predefine the cluster number. In order to overcome these shortcom- ings, we propose an automatic clustering algorithm, fast black hole-spectral clustering （FBH-SC）. The FBH algo- rithm is used to replace the K-mean method in SC, and a CritC index function is used as the target function to automatically choose the best scale parameter and clus- tering number in the clustering process. Different simulation experiments were designed to define the relationship among scale parameter, clustering number, CritC index value, and clustering accuracy. Finally, an example is given to validate the effectiveness of the proposed algorithm.

Approach to the Design Calculation of Sucker Rod Pumping Systems in Coalbed Methane Wells

The existing design of the pumping systems mainly focuses on the approximate computational formulae and procedures,which are developed based on the analytic approaches of conventional oil/gas fields.The calculation of polished rod loads usually just concerns about the static and inertial loads.And the computation of gearbox torque generally uses empirical formulae and correction factors.The above modeling procedures,if applied to the coalbed methane（CBM） wells,can not give the desired accuracy of the system design and its pertinent analysis.In this paper,based on the kinematic and dynamic analysis of the pumping system,the kinematic relation of polished rod is analyzed,and the variation of the total loads of polished rod is developed with the limits of CBM well conditions along the string.The gearbox torque calculation model is established by combining the counterbalance effect with the calculated dynamometer cards and torque factors.The application characteristics of this model are demonstrated by the example of ZH002-4 well in Qinshui basin.The interpretations of results show that the cranks of beam units should rotate in a counter clockwise direction viewed with the wellhead to the right.Compared with oil？gas fields,the dynamic and friction to polished rod load ratios are relatively high and the computation of polished rod loads should involve the static and inertial loads,as well as vibration and friction loads.And the dynamic load ratio decreases rapidly during the production.Besides,the total deformation of the string is small in CBM wells.As for balanced operation,the gearbox torque load usually has two approximately equal peaks and the magnitudes of instantaneous torque are just within 50% of unbalanced gearbox loadings.The proposed research improves efficiency of the pumping system,loads the pumping unit more uniformly,and provides the reasonable basis for selecting the units.

Fluid characteristic of multiphase fluid in annular space between pump barrel and plunger

The pump performance parameters,such as pump pressure,plunger friction and pump valve resistance,are fundamental parameters of optimal design of pump efficiency and sucker rod pumping system (SRPS).In this paper,considering the characteristic of geometrical nonlinear and rheology property of multiphase fluid,the pump performance parameters are studied.Firstly,a dynamics model of annular fluid flow is built.In the detail,a partial differential equation of annular fluid is established and a computing model of fluid pressure gradient is built.Secondly,the simulation models of plunger friction and hydraulic resistance of pump valve are built.Finally,a novel simulation method of fluid pressure in annular space is proposed with software ANSYS.In order to check up the correction of models proposed in this paper,the comparison curves of experiment and simulation results are given.Based on above model,the whole simulation model of plunger pump is simulated with Visual Basic 6.0.The results show that the fluid friction of pump plunger and instantaneous resistance of pump valve are nonlinear.The impact factors of pump performance parameters are analyzed,and their characteristic curves are given,which can help to optimize the pump motion parameters and pump structural.

Ultrastructure Observation of Cysticercus Pisiformis and Its Function Analysis

[ Objective] The aim of the study was to observe the ultrastructure of Cysticercus pisiformis under different state. [ Method] The Cysti- cercus pisiformis were obtained in the procedure of slaughter inspection form meat-packing plant. The Cysticercus pisiformis was taken out by cut- ting cyst directly, or cultured with physiologic saline containing 10% bile until evagination. Then it was observed and recorded by scanning electron microscopy. [ Result] Observed from top of scolex of Cysticercus pisiformis locate in cyst, the rostellum looked like an umbrella. The cutaneous muscular columns with hamula covered the front end of scolex. Viewed from the side, a row of antlers-liking hamula adhered to the scolex. Four suckers were looked like more width and body segments less time, in which there were lots of wrinkles in their surface respectively. The Cysticercus pisiformis cultured was divided obviously into scolex, neck, body segment and zone of cyst. When cutaneous muscular column of rostellum con- tracted, the antler-liking hamula extended to periphery that the ring-liking contraction appeared in neck and the lengthways contraction in body seg- ments. [ Conclusion] The Cysticercus pisiformis under different state has distinctly dissimilar ultrastructure.

Adaptive fault diagnosis of sucker rod pump systems based on optimal perceptron and simulation data

A highly precise and timely diagnosis technology can help effectively monitor and adjust the sucker rod production system(SRPS)used in oil wells to ensure a safe and efficient production.The current diagnosis method is pattern recognition of a dynamometer card(DC)based on feature extraction and perceptron.The premise of this method is that the training and target data have the same distribution.However,the training data are collected from a field SRPS with different system parameters designed to adapt to production conditions,which may significantly affect the diagnostic accuracy.To address this issue,in this study,an improved model of the sucker rod string(SRS)is derived by adding faultparameter dimensions,with which DCs under 16 working conditions could be generated.Subsequently an adaptive diagnosis method is proposed by taking simulated DCs generated near the working point of the target SRPS as training data.Meanwhile,to further improve the accuracy of the proposed method,the DC features are improved by relative normalization and using additional features of the DC position to increase the distance between different types of samples.The parameters of the perceptron are optimized to promote its discriminability.Finally,the accuracy and real-time performance of the proposed adaptive diagnosis method are validated using field data.

Dynamic simulation and efficiency analysis of beam pumping system

An improved whole model of beam pumping system was built. In the detail, for surface transmission system(STS), a new mathematical model was established considering the influence of some factors on the STS's torsional vibration, such as the time variation characteristic of equivalent stiffness of belt and equivalent rotational inertia of crank. For the sucker rod string(SRS), an improved mathematical model was built considering the influence of some parameters on the SRS's longitudinal vibration, such as the nonlinear friction of plunger, hydraulic loss of pump and clearance leakage. The dynamic response and system efficiency of whole system were analyzed. The results show that there is a jumping phenomenon in the amplitude frequency curve, and the system efficiency is sensitive to motor power, pump diameter, stroke number, ratio of gas and oil, and submergence depth. The simulation results have important significance for improving the efficiency of beam pumping system.

Effect of Produced Fluid on the Wear Behavior of Grade D Sucker Rod and N80 Type Tubing

Inuestigated wear tests of grade D sucker rod and N80 tubing with a produced liquid are the effect of the water cut of produced liquid on the wear rate and the wear coefficient of the friction pair. And presented here is a comparison of tribological performance of tubing/sucker rod with sprayed tubing/sucker rod and tubing/sprayed sucker rod. The results show that one of the main reasons for wear failure between the sucker rod and the tubing is a high water cut of the produced liquid. The wear rate increases greatly when the water cut ranges from 70% to 85%, and increases gradually when the water cut is less than 70% or more than 85%. The higher the water cut is, the greater the wear rate will be. SEM (scanning electron microscope) micrographs show that the worn surface of the tubing is smoother, with shallow grooves, when the water cut is 55%; when the water cut is 95%, there are broader and deeper grooves on the worn surface. The results also show that the wear rate of the sprayed wear-resistant coating of sucker rod/tubing is less than that of the unsprayed sucker rod/tubing.

Online Magnetic Flux Leakage Detection System for Sucker Rod Defects Based on LabVIEW Programming

Aiming at the detection of the sucker rod defects,a real-time detection system is designed using the non-destructive testing technology of magnetic flux leakage(MFL).An MFL measurement system consists of many parts,and this study focuses on the signal acquisition and processing system.First of all,this paper introduces the hardware part of the acquisition system in detail,including the selection of the Hall-effect sensor,the design of the signal conditioning circuit,and the working process of the single chip computer(SCM)control serial port.Based on LabVIEW,a graphical programming software,the software part of the acquisition system is written,including serial port parameter configuration,detection signal recognition,original signal filtering,real-time display,data storage and playback.Finally,an experimental platform for the MFL detection is set up,and the MFL measurement is carried out on the transverse and longitudinal defects of the sucker rod surface.The experimental result shows that the designed acquisition and processing system has good detection performance,simple design and high flexibility.

Novel sucker rod pumping system based on linear motor technology

Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping units have many intrinsic disadvantages such as low efficiency, complex transmission devices, poor flexibility, tremendous volume and weight in long stroke, etc.Therefore, a novel direct driven linear electromagnetic pumping unit (EMPU) has been developed by combining oil extraction technology with linear motor technology. The thrust of EMPU matches the changing of suspension center load to improve the system efficiency and cut down the consumption of energy. Based on previous experience, a small-scale prototype was developed and a simulation was conducted with it. Both theoretical analyses and experimental study showed that the problems exiting in beam pumping units can be solved with EMPU system, and this is a new method which can be used to solve high energy waste in oil fields.

CONTROL AND SELECTION OF STRUCTURE PARAMETERS OF ADAPTIVE SUCKING DISK

This paper introduces a kind of sucking disk that consists of many microsuckers which can work on a noncontinuously smooth surface. The control technology and selection principle of basic structure parameters of this sucking disk are also presented.

Research on Alternatively Moving Vacuum Absorbing Wall-climbing Robot

In conection with the complex working-surroundings of the wall-climbing Robot, this paper researched akind of alternatively moving mechanism with good obstacle-surmounting ability and high moving speed, making use ofthe thought of bionics. This paper designed a kind of self-adjusting multi-vacuum sucker. Furthermore, it employedthe theory of vacuum system to establish the work mathematics madel of control switch to are sucking disc and presented the design parameter of the control switch. In addition, this paper made use of the thought of bionics to design aobstacle-surmounting mechanism used in wall-climbing robot. Also it employed the theory Of robotics to analyze the kinematics and the dynamics movement of die robot.