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Background: For intra-articular calcaneal fractures of Sanders type II and above, open reduction and internal fixation could obtain anatomic reduction and firm fixation, however, there are high complications associated with surgery, such as incision infection and subtalar joint stiffness. As another treatment method, poking reduction and percutaneous fixation can reduce the complications. In this study, we introduce a new technique for external fixator-assisted reduction and computer-assisted preoperative design of the poking reduction and percutaneous screw fixation.Methods: Patients with calcaneal fractures who met the inclusion criteria were treated with external fixator-assisted poking reduction and percutaneous screw fixation at our hospital from March 2017 to September 2019, and the clinical and radiographic outcomes were evaluated.Results: A total of 31 patients were followed up, 10 cases of Sanders type II, and 21 cases of Sanders type III calcaneal fracture. The mean time from injury to operation was 3.2±1.9 days; the mean hospital stay was 7.3±3.1 days; the mean operation time was 87.74±30.30 min; and the mean intraoperative blood loss was 41.45±34.16 ml. Two patients underwent a change of surgical procedure and one underwent a second operation. Postoperative follow-up radiography showed good reduction of calcaneus length, height, width, Böhler angle, and Gissane angle. Postoperative follow-up CT showed good reduction of the subtalar articular surface in 83.6% of patients. At the last follow-up, the AOFAS score was 93.84±7.92, of which 24 cases were excellent, six cases were good, and one case was acceptable. The average range of motion of flexion and extension of the ankle joint on the injured side was 64.35±1.38°, which was not statistically different from that of the healthy side. The average range of motion of the subtalar joint was 29.27±1.63°, which was 88.6% of the healthy side, and two patients developed subtalar traumatic arthritis.Conclusion: External fixator-assisted poking reduction and percutaneous screw fixation is a safe and effective minimally invasive surgery for intra-articular calcaneal fractures, which has a lower incidence of postoperative complications and can reduce the impact on subtalar joint mobility, and increase the clinical effect. Trial registration: Retrospective cohort study.

To improve the long-term outcomes of high tibial osteotomy (HTO) for gonarthritis, many cartilage repair procedures appeared, but their effects were controversial. To evaluate the efficacy of cartilage repair procedures during HTO for gonarthritis, we performed this update meta-analysis. We performed the system retrieval for clinical trials using various databases and then pooled the outcomes of the included studies. Fifteen studies were involved. The pooled results indicated that there were no significant differences in Kellgren and Lawrence (KL) scale (mean difference [MD] = 0.02, 95% confidence interval [CI] = −0.01 to 0.06, p = 0.24), the femorotibial angle (MD = 0.06, 95% CI = −0.04 to 0.16, p = 0.22), and magnetic resonance imaging (MRI) outcomes (MD = 12.53, 95% CI = −2.26 to 27.32, p = 0.10) of patients in experimental group than control. The subgroup analysis showed that the clinical outcomes of abrasion arthroplasty (AA) were worse than control group (standardized mean difference [SMD] −2.65, 95% CI = −3.67 to −1.63, p

HLP type hydraulic oil has wide application in aerospace field. The existing measurement method of Laval nozzle throat diameter efficiency is low, and has the potential to cut parts surface. Therefore, a non-contact throat diameter measuring method based on the hydraulic oil is proposed. Then the flow field is simulated, and measurement parameters are calculated. The flow field analysis results show that this method is suitable for measuring Laval nozzle throat diameter.

Passive torque servo system (PTSS) is a key equipment in the hardware-in-the-loop experiment for the test of actuator performance. A novel mathematical model was obtained by analyzing the structure and working conditions of PTSS in this paper and the model was analyzed with the matlab software. PID controller was used to correct the actuator system and the result is effective. The disturbance torque was analyzed on different frequency of command signal, it was found that the disturbance torque increases, and with the phase ahead of the signal, but the amount of lead decreases with variation of frequency of command signal. Three components of the disturbance torque were obtained by theoretical analysis, and the reverse current compensation method was composed. It was found that the proportion of three parts of disturbance torque changed with increasing frequency of command signal and the reason of the variation was analyzed. Finally, the theoretical analysis of the construction of disturbance torque was correct by the comparison of the result of simulation.

HLP type hydraulic oil has wide application in aerospace field. This paper discusses HLP type hydraulic oil’s performance. Then a new meso-scale hole measurement method is proposed base on HLP type hydraulic oil’ characteristic. Several groups of measurement experiments with different measuring parameter are done. The experiment results show that using HLP type hydraulic oil in meso-scale hole is suitable and effective.

The electro-hydraulic servo valve is the essential component of the electro-hydraulic servo control, and it was mainly used on many fields such as aviation, aerospace and navigation etc.People use the electro-hydraulic servo valve to drive plenty of loads. The electro-hydraulic servo valve has many advantages such as fast dynamic response, high control precision, and longevity. Hence, for the elastic element of the electro-hydraulic, which works as the significant feed-back component the characteristic of the stiffness has played an essential role in the electro-hydraulic servo. Based on the previous research of the technology automation and inspection experiment, this paper proposes an auto-stiffness admeasuring apparatus for the elastic element of the Hydraulic servo. and the experiment research has been proceeded. The experimental result shows that, the auto-stiffness admeasuring apparatus has the advantages of high precision, high automation; it can be well used in the productive practice.

Electro-hydraulic servo valve is the key component of an electro-hydraulic servo control system, and double nozzle flapper valve is the main type of electro-hydraulic servo valve. Nozzles are the important part of a double nozzle flapper valve, the pairing quality is directly related to the performance of the servo valve .Servo valve is of symmetrical structure, and the use of nozzles is also in pairs. The process of nozzles matched in pairs is called pairing process. Because the orifice diameter of the nozzle is only about 0.2 to 0.3 mm, it is difficult to pair with the method of direct measurements. Besides, as a kind of hydraulic components, nozzles are usually paired by flow rate measured under differential pressure. Two nozzles will be matched to a pair if their pressure-flow rate characteristic curve is within the allowed tolerance. To ensure the success rate of pairing, it usually needs a large number of machined nozzles to be sifted. According to the principle of clustering analysis, we propose a new paring algorithm which can match nozzles efficiently and automatically.

This paper proposes a hydraulic measurement model for measuring the Laval nozzle throat diameter size. Based on measurement principle of liquid pressure – flowrate, we can get the size of Laval nozzle throat diameter by measuring the fluid flowrate through hydraulic measurement model at the fixed pressure. With good viscosity-temperature performance, low temperature performance and oxidation stability, UCBO aviation hydraulic oil is selected as the measuring medium. In the hydraulic measurement model, the diameter of the mandrel which can be regarded as gauge will directly affect the sensitivity of diameter measurement. Therefore we need to optimize the design of the mandrel of the hydraulic model.

In this paper a new kind of finite element analysis model towards metallic microstructure of titanium alloy is established based on a common metallic microstructure picture. By the simulation of tensile test on this new kind of FEA model performed by finite element analysis software Abaqus, the tensile curve in the state of simulation is obtained. Meanwhile, in order to verify the accuracy of the simulation results, a series of tensile tests are designed and performed and the tensile curves under experimental conditions are obtained. Comparing the experimental results with the simulation results, the conclusion can be verified that the new microstructure FEA model can illustrate the metallic microstructure very well. And this model provides a new perspective to study the mechanical properties of metallic materials.

To evaluate the effectiveness of autologous vein nerve conduit supported by vascular stent in repairing a 10 mm gap peroneal nerve in white New Zealand rabbits.30 New Zealand rabbits were randomly divided into three groups: autologous nerve group (group A),conventional autologous vein nerve conduit group (group B),autologous vein nerve conduit supported by vascular stent group (group C). 10 mm common peroneal nerve was cut off. In groups A,the peroneal nerve was turned 180 ° before suturing. In group B and group C,20 mm long external jugular vein was cut and removed. After dilution of venous retraction,the venous bridge filled the gap of the nerve defect in group B. In group C,a blood vessel stent was placed for accessing the external jugular vein,and then connected to the nerve defect. Ulnar ulcer was observed after operations. Reflex score of left foot toe was recorded. The nerve regeneration and functional recovery was assessed through electrophysiological examinations,comparison of wet mass ratio between the left and right hind limb gastrocnemius,morphological observations,transmission electron microscopy 12 weeks after operations.Group B had the lowest scoring of toespreading reflex,whereas Group A had the highest scoring of toespreading reflex. There was a statistically significant difference in the scoring of toespreading reflex between group A and group C. In terms of the diameter of regenerated nerve fiber and the thickness of regenerated myelin sheath,no statistically significant (Autologous vein nerve conduit supported by vascular stent increases regeneration of nerves.

To compare the effectiveness of two lumbopelvic fixation procedures for treating unstable sacral fractures.The clinical data of 47 patients were treated for unstable sacral fractures in the West China Hospital of Sichuan University from January 2010 to December 2014 were reviewed. Twentytwo patients (28 sides) were treated with USS combined with iliosacral screw (group A),while 25 patients (39 sides) were treated with closed multiaxial screws (CMAS) iliosacral fixation system combined with Posterior Segmental Spinal Fixation system (group B). The outcomes of the two procedures were compared using the following indicators: length of operations,amount of intraoperative blood loss,MATTA score of fracture reduction,MAJEED function score one year postoperation,postoperative complications,and GIBBONS Classification of sacral nerve injury in patients with sacral nerve symptoms.Group A had longer operations [(121.4±5.1) min] than group B [(110.6±4.5) min,CMAS iliosacral fixation system is better for treating unstable sacral fractures compared with USS combined with iliosacral screws.

Pelvic fracture is one of the common diseases of traumatic orthopedics. With the increase of accidents such as traffic accidents,high craters and crush injuries in China,the incidence of pelvic fractures is also increasing year by year. Since pelvic bones and the ligament structure are close to neurovascular,cavity organs and the urogenital structure,early diagnosis and treatment of pelvic fractures is essential for preventing early complications and late sequelae. The treatment of pelvic ring injury has been the focus of pelvic fracture treatment,which determines the outcome of treatment. The application of external fixation and internal fixation to pelvic fracture is still subject to ongoing debate. For unstable pelvic ring injury,emergency external fixation plays a very important role. Pelvic ring injury is often accompanied with nerve injury (lumbosacral plexus injury),which often leads to pain,dysfunction and other complications. Because of its refractory,extensive studies have been undertaken to identify clinical innovations that may be able to repair nerve damage and reduce complications. These research advances can help improve the diagnosis and treatment of pelvic fractures and patient survival and prognosis.

To compare the efficacy of sacroiliac joint anterior approach with double reconstruction plate and computer assisted navigation percutaneous sacroiliac screw for treating Tile C1 pelvic fractures.Fifty patients with pelvic Tile C1 fractures were randomly divided into two groups (No significant differences in baseline characteristics were found between the two groups of patients. All of the patients in both groups had their operations successfully completed. Patients in group B had significantly shorter operations and lower intraoperative blood loss,incision length and postoperative complications than those in group A (Sacroiliac joint anterior approach with double reconstruction plate and computer assisted navigation percutaneous sacroiliac screws are both effective for treating Tile C1type pelvic fractures,with similar longterm efficacies. However,computer assisted navigation percutaneous sacroiliac screw has the advantages of less trauma,less bleeding,and quicker.

To develop a renewed classification and treatment regimen for sacroiliac joint dislocation.According to the direction of dislocation of sacroiliac joint,combined iliac,sacral fractures,and fracture morphology,sacroiliac joint dislocation was classified into 4 types. Type Ⅰ (sacroiliac anterior dislocation): main fracture fragments of posterior iliac wing dislocated in front of sacroiliac joint. Type Ⅱ (sacroiliac posterior dislocation): main fracture fragments of posterior iliac wing dislocated in posterior of sacroiliac joint. Type Ⅲ (Crescent fracturedislocation of the sacroiliac joint): upward dislocation of posterior iliac wing with oblique fracture through posterior iliac wing. Type ⅢA: a large crescent fragment and dislocation comprises no more than onethird of sacroiliac joint,which is typically inferior. Type ⅢB: intermediatesize crescent fragment and dislocation comprises between one and twothirds of joint. Type ⅢC: a small crescent fragment where dislocation comprises most,but not the entire joint. Different treatment regimens were selected for different types of fractures. Treatment for type Ⅰ sacroiliac joint dislocation: anterior iliac fossa approach pry stripping reset; sacroiliac joint fixed with sacroiliac screw through percutaneous. Treatment for type Ⅱ sacroiliac joint dislocation: posterior sacroiliac joint posterior approach; sacroiliac joint fixed with sacroiliac screw under computer guidance. Treatment for type ⅢA and ⅢB sacroiliac joint dislocation: posterior sacroiliac joint approach; sacroiliac joint fixed with reconstruction plate. Treatment for type ⅢC sacroiliac joint dislocation: sacroiliac joint closed reduction; sacroiliac joint fixed with sacroiliac screw through percutaneous. Treatment for type Ⅳ sacroiliac joint dislocation: posterior approach; sacroiliac joint fixed with spinal pelvic fixation.Results of 24 to 72 months patient follow-up (mean 34.5 months): 100% survival,100% wound healing,and 100% fracture healing. Two cases were identified as type Ⅰ sacroiliac joint dislocation,including one with coexistence of nerve injury. Patients recovered completely 12 months after surgery. Eight cases were identified as type Ⅱ sacroiliac joint dislocation; none had obvious nerve injury during treatments. Twelve cases were identified as type Ⅲ sacroiliac joint dislocation,including one with coexistence of nerve injury. Patients recovered completely 12 months after surgery. Three cases were identified as type Ⅳ sacroiliac joint dislocation with coexistence of nerve injury. Two patients fully recovered 12 months after surgery. One had partial recovery of neurological function.The classification and treatment regimen for sacroiliac joint dislocation have achieved better therapeutic effect,which is worth promoting.

This article analyzes the deviation of existing stiffness measurement method and comes to the main components of the measurement error. Focus on the influence of the bending deformation all of aspects and contact deformation between the various links to the measurement accuracy. Establish the relationship between the actual deformation and the measured deformation to the spring tube through homogeneous coordinate transformation and finite element analysis, in order to identify the error sources impact on the measurement greatest, and improve the measure methods to against the main error source, eliminate the influence of the main error source to the stiffness measurement, then achieve the purpose of improving the measure accuracy.

This article describes the elastic element of the servo valve, elaborates the definition of the stiffness of elastic element, analyzes the characteristics of existing rigidity measurement system, points out the limitations of the existing rigidity measurement system when it measures the large-stiffiness elastic element, utilizes a new measuring principle based on the existing stiffness test systems, uses the more accurate laser displacement measurement method to overcome the weaknesses of the existing stiffness test system, improves the measurement accuracy, makes stiffness measurements more accurate and promotes the stiffness measurement technology of the servo valve elastic element.

Torque motor is an electrical-mechanical converter of servo valve, is bridge which connects the electrical devices and hydraulic devices, is one of key components of servo valve. The permanent magnet torque motor is studied in this paper. As key parameters of design of servo valve, the magnetic property of torque motor determines magnitude of the electromagnetic torque. At present, many manufactures of servo valve pays more attention on the test of integral servo valve. The design of torque motor also bases on experience, lacking of specialized tool for torque motor test. This paper described the principle of magnetic property of the test, developed a test system for magnetic characteristics, and established the relationship between the electromagnetic torque and current control current, and the relationship between output angular displacement and control current.

Pressure type pneumatic measuring is the most wildly used method in overlap value testing, which depends strongly on the constant pressure of gas supplying. However,control of pressureisrarely done before.This paper presentsa design of a new overlap value measuring system with pressure control sub-system, mechanical platformand a program-controlled sub-system. A hybrid controller is developed combined with fuzzyself-adjusting PID and time-optimal control. The final version of this controller is a computationally efficient analytic scheme suitable for implementation in thereal-time closed-loop pressure digitalcontrol. At last, the system control software developed on LabVIEW is briefly introduced.

This paper introduces the defect formation and compensation method of Invar during hot stamping with multi point flexible mould. In cylindrical and spherical, for example, through Solidworks 3-d modeling, using Dynaform to do forming numerical simulation, we study multi point hot stamping defects of thick Invar, mainly including indentation and rebound. Then we get the rules of indentation and rebound with thickness and curvature, compensate these defects and control the error within the requirements.

Torque motor is the electrical - mechanical converter of servo valve, is the bridge connecting electrical devices and hydraulic devices, is one of the key elements of electro-hydraulic servo valve. The main object of study of this paper is moving iron permanent magnet torque motor. The dynamic characteristics of torque motor are the key parameter to measure the overall performance. At present, the research of most of manufacturers emphasize on the test of integral valve servo valve. Torque motor is also designed to mimic the structure and size of foreign-based valve, lacking of system understanding for characteristics of servo valve. Early in the design, people cannot effectively control the overall performance of the torque motor products. There is large performance difference with a larger group of torque motor, producing serious waste. This paper describes the principle of dynamic characteristics test, establishes a test system of dynamic characteristics for torque motor, accurately obtain nature frequency and bandwidth of torque motor on the test bench which we have established before.

This document explains how to transform an ordinary float-type pneumatic measuring instrument by adding a right lights sensor on it. Then we design a suitable float for it through the theoretical calculation and the simulation with Fluent. At last, the research do a series of experiments and by the experiments, its nonlinear error is less than the ordinary float-type pneumatic measuring instrument. So the whole instrument is feasible. The final purpose of designing the float-type pneumatic measuring instrument based on the red lights sensor is to measure the overlap of the valve core & sleeve of the slide valve.

Dual inverter fed open-end winding induction motor (OEW-IM) is a new solution for multilevel drive. Comparing with traditional multilevel converters, the dual inverter is being interested in for its more flexible current control, the absence of fluctuating neutral point, and fault-tolerant capability. This paper analyzes the potential common-mode voltage (CMV) in the open-end winding induction motor system, and proposes a new space vector PWM (SVPWM) strategy to reduce the CMV. The proposed method is validated by simulations and experiments.

Objective: To analyze the early clinical and radiographic outcomes of Hoffa fractures treated by a standard protocol of open reduction and internal fixation using headless compression screws combined with back buttress plate in a consecutive series of 8 Chinese patients. Methods: Open reduction and internal fixation was performed on all patients. The fractures were anatomically reduced and held temporarily by K-wire. If the ends of fractures were atrophic, autologous bone graft from the ipsilateral iliac crest was packed between the ends. Then the fracture fragments were fixed with AO 6.5 mm headless compression cannulated screws. At least two screws were used to provide rotational stability. One pre-contoured reconstruction plate was placed on the nonarticular surface posteromedially or posterolaterally as back buttress plate. Results: All the patients were followed up for at least 12 months (range 12-25 months). All fractures achieved anatomical reduction and healed clinically and radiographically. At recent follow-up, the mean flexion degree was 120.6° (range 110°-135°) and the mean extension degree was 2.5° (range 0°-5°). The average visual analogue scale score was 1.6 points (range 0-3). Six patients were assessed as excellent and 2 as good according to the hospital for special surgery knee score system. There were no superficial or deep infections, or hardware breakages. No patient had giving way or locking of the knee, though some had intermittent pain and swelling after strenuous exercise. Injury mechanism had significant influence on the functional outcome (P=0.046).Conclusion: Headless compression screws combined with back buttress plate and/or autologous bone grafting to treat old Hoffa fracture is one of effective measures. It would be conducive to not only fracture healing but also early exercise and functional recovery. Key words: Fractures, bone; Fracture fixation, internal; Intra-articular fractures

A segmental long bone defect in a rabbit radius nonunion model was repaired using cylindrical porous titanium (Ti) and hydroxyapatite (HA) scaffolds. Each scaffold was produced using the same method, namely, a slurry foaming method. Repairing ability was characterized using x-radiographic score 12 and 24 weeks postprocedure; failure load of the radius-ulna construct, under three-point bending, 12 weeks postprocedure; and the percentage of newly formed bone within the implant, 12 and 24 weeks after postprocedure. For each of these parameters, the difference in the results when porous Ti scaffold was used compared with when HA scaffolds were used was not significant; both porous scaffolds showed excellent repairing ability. Because the trabecular bone is a porous tissue, the interconnected porous scaffolds have the advantages of natural bone, and vasculature can grow into the porous structure to accelerate the osteoconduction and osteointegration between the implant and bone. The porous Ti scaffold not only enhanced the bone repair process, similar to porous HA scaffolds, but also has superior biomechanical properties. The present results suggest that porous Ti scaffolds may have promise for use in the clinical setting.

Brake caliper unit with intricate structure is the last guarantee device for trains braking, while technology in this aspect is still backward. RE of advanced equipments is an effective and fast way to improve the existing situation. But efficiency and accuracy would be lost if the reversing program is planned in unappreciated way. In view of this, a whole RE scheme for the certain unit was presented in this paper. Multi-measurement was adopted that integration of conventional measurement and 3-D digital measurement was proposed. Based on analyses of structure and function of the crucial parts, feature decoupling was given obeying the principle of data segmentation. From which basic feature groups were extracted as bases of further measure method choosing. Functions of mechanism and demands of precise assembly were all taken into consideration to ensure the high accuracy and efficiency. With help of the optimal matching between structure feature and certain measurement, geometric information digitization was realized and the existing status of excessive point cloud data caused by single measurement was improved. As to part model reconstruction, characteristic curves were fitted in Imageware environment. Taking point clouds as reference, CAD models of parts were built in Pro/E environment. A general process of reverse engineering of complex structural components was stated.

In this paper, a mathematical model of the loading system is established. The characteristics of the loading channel and disturbance channel are analyzed through this mathematical model. Analysis results show that the loading channel is unstable and disturbance torque leading the input command. It directly impact on the output torque, serious affect the systems loading precision. Characteristics of the loading system are analyzed, and the results show that stiffnesss effect on the loading system is twofold, should be considered at the same time. Reduce the system's moment of inertia is good for the characteristics of the loading system.

This article aims to optimize the clamp arm's length and the number and shape of the slots of the spring-tube fixture. First it uses the theory of elasticity to create the force deformation model of slot with regular shape, and analysis the deformation of the slot numerically. Then draws the relationship between the elastic deformation and the radius of the bore and the arms length while the force is not change, and comes an ideal shape of the bore through this relationship. It also simulates the deformation of fixture with different number of modified slots through the finite element analysis method, and optimizes the fixture for equal strength further. In summary it comes to meet the requirements of fixture theoretically. Finally through experiments the theory gets verified. From the results of experiments the conclusion can be drawn that the corrected fixture is better than before.

Raising a pneumatic measurement method to measure the valve sleeve bores cylindricity based on error compensation. Analysis related errors of the raised measurement method, determined the maximum error, and setting up the error compensation model to the maximum error, designed the measurement system, related experiment has been conducted, which verified the correctness of the measurement method and the accuracy of the measurement system.

During the processing of the servo valve spool machining, the overlap of valve spool's each edge should take zero grinding. The grinding processes including spool overlap test and grinding. In this paper, the authors used a new test method, which simulates working condition of servo valve. Hydraulic cylinder is used as the load of servo valve in this test method, and the hydraulic cylinder is in no-load operation. This test method realized the automatic switch of test valve, and it determined the amount of grinding through complete measuring four edges overlap values, furthermore, it realized measuring the total amount of overlap, thus reflect the flow characteristics of a valve. This is a new automatic method for measuring servo valve overlap.

Disposable mechanical elements are widely used in many fields such as aerospace and military industries. It is known for their extremely short work time which is quite different from general mechanical elements. The stress level of disposable mechanical elements is much higher than general mechanical elements. In this situation, the traditional fatigue fracture failure will be replaced by fatigue elastic failure used in the design of disposable mechanical elements. The fatigue elastic failure is closely related to the ratcheting properties of materials. Therefore, this paper focuses on the ratcheting properties of typical cyclic softening materials steel 45 and 42 CrMo. The fatigue elastic failure phenomenen of these two materials are shown through the stress control tests.

The disturbance torque which is caused by the interference of the motor position has observably impact on accuracy of the loading system. According to unstable loading channel and disturbance torque, this paper use a complex control algorithm of differential forward PID control and feed-forward compensation. At the end of this paper, the simulation analysis results show that the feed-forward compensation can observably eliminate the influence of the disturbance torque, and improve the accuracy of the loading system.

The quality of thread will directly affect the reliability of mechanical system, and the accuracy grade of geometric parameters is the judgment standard to thread quality. Thus, its particularly important to detect the geometric parameters of thread. Its a pretty mature and widely used method to measure thread parameters with universal tool-measuring microscope, but it has many shortcomings, such as tedious operation, low efficiency and the reading error. In view of the above shortcomings, the paper does some simple refits to the existing 19JA universal tool-measuring microscope. In order to improve reading speed and accuracy, the grating rulers are installed on the operating platform in two directions. CCD camera is used to get external thread image instead of human eyes and the eyepiece, which is a non-contact measurement method. A software that based on MFC of VC + + 6.0 is written, which can deal with the thread image and get the thread parameters. The experimental results show that the method can not only effectively improve the measurement efficiency but also guarantee the accuracy of measurement.

As a pressure regulating component, pneumatic control valve has been widely used in control system. The stability of its performance not only concerns the control precision, but also has direct influence on the systems normal operation. Thus, a test on the valves characteristics before putting into use is rather important. According to analysis of testing requirements, this paper determined the overall program of this pneumatic measurement system, designed the gas-circuit, provided specialized software for measurement, and developed an automatic test system. The experimental data shows the system is with high precision and can satisfy the needs of valve test well.

Aiming at additional load consisted in jumping performance testing of actuator at present, the paper designed a testing system of mechanical speed jumping performance, and made compensation calculation by shortening the corresponding time of reach a certain speed point. At last, the compensation method was verify that correct and feasible by simulation experiments.

This paper studies a load simulation system based on permanent magnet synchronous motor. Vector control principle of the loading motors vector control technology is analyzed, and using the strategy that direct-axis component of the stator current is zero, the mathematical model of load control is established. To analysis the control characteristics and lay a foundation for the control algorithm of the system, the control channel is divided into two channels, namely the forward load channel and disturbance channel, whose characteristics are analyzed, too. The torsional stiffness of the connecting link has an effect on the dynamics characteristics of the system. Therefore, the system dynamic characteristics under different torsional stiffness of forward load channel and disturbance channel are analyzed in the paper.

Armature components are the core component of the electro-hydraulic servo valve, and all the components of the armature components require high precision and assembly accuracy. Now, the armature components assembly uses an old-fashioned pressing machine, whose success rate and efficiency are low. This situation wastes a great deal of economic costs and time costs. To improve this situation, the authors develop a new type of automatic assembling machine to achieve automatic and high-precision assembly of the armature component.

The armature components are the core component of the electro-hydraulic servo valve [. Its manufacturing and assembly accuracy directly affects the performance of the servo valve. The domestic existing electro-hydraulic servo valve armature assembly pressure equipment is so far behind that it is difficult to meet production requirements. For the needs of a servo valve production firm, authors department developed the armature components automatically press machine. In order to achieve automation and intelligent of press process, this article supports a electronic control system for the press machine to further improve its ability. And on the basis of certain experiments, the author proves the good performance of the pressure machine.

This paper describes machining trajectory generation and simulation of miniature integral impeller. Taking into account the closed and miniature of integral impeller, and low stiffness of the micro-milling tool, in order to avoid interference in the processing, through reasonably division of the impeller blade surface, generate the miniature integral impeller machining trajectory. Then impeller machining NC code is generated, and is simulated in Vericut software. Simulation result shows that the machining programs generated in this paper are effective, and the simulation machined workpiece surface is relatively smooth.

The curve intensity of deddendum plays a significant role in gear strength design. Due to the complicated shape of gears, traditional method utilizes the cantilever beam model adds the concentrated load at a fixed point and then revises it by coordinating with different factors so as to calculate the gears the curve intensity of deddendum. In this paper, based on evolute formulas, a methodology about finite element analysis was used for establishing the accurate tooth profile model of the evolute cylinder gear. The moving load was added by programming and the regularity that the amplitude of load changes with the position of the point of application in a tooth meshing cycle was determined. Based on proposed model, this paper provides the variation regularity of the magnitude of the stress of deddendum by simulation.

Setting up the FEM model of a spacecraft catheter connector, analysis its static strength and optimized its structure, Shorten the diameter and reduced the weight of catheter connector, within the requirement of properties.

This paper takes a kind of 14 mm inner diameter, installation span for 600 mm conduit connector as an example to do the top 5 order modal analysis, resonance resistance analysis and random vibration analysis and gets the vibration model in the different frequency.

As an important component of the fasteners members, threads quality, depending on whether its geometric parameters meet requirements or not, will affect the reliability of the whole machine system. Therefore, geometrical parameters measurement of the thread is especially important. Aiming at the characteristics of the thread teeth type, this paper adopt a machine vision measurement method based on the universal tool microscope and CCD .This paper also analyzes the causes and influences of the teeth shading and proposes a corresponding improvement method, specific to the shading problem in the process of backlighting projection. After experimenting, this method can effectively improve the accuracy and efficiency of the male parameters measurement.