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Taking the point contact gear with circular-parabola configuration as the research object, based on the Adams dynamic analysis software, dynamic characteristics and the variable law of tooth surfaces are studied in this study. Firstly, according to space meshing theory, tooth surfaces equation of the point contact gear with circular-parabola configuration is derived, and three-dimensional solid models of gear pairs are established by the given design parameters. Secondly, the virtual prototype of point contact gears with circular-parabola configuration is established utilizing Adams software. Through simulation process, variation law of normal contact force, circumferential force, radial force and axial force of the gear are discussed. Change law of normal contact force under the same parameters and working conditions are analyzed between the point contact gear with circular-parabola configuration and general involute helical gears. Influences of meshing stiffness on normal contact force of the gear are also discussed. Research results show that the dynamic performance of point contact gears with circular-parabola configuration is better than that of general involute helical gears under the same parameters and working conditions. Meshing stiffness has a certain influence on the dynamic performance of tooth surfaces. For a reasonable variable range, the transmission process will be more stable with the increase of the meshing stiffness. The study can provide a basis for the design of point contact gears with circular-parabola configuration.

Aiming at the tooth profile contact problem of internal meshing gear transmission pairs with double contact points, the generation method of tooth profiles of the internal meshing gear transmission pair with double contact points is present. Based on Hertz contact theory, the mathematical model of instantaneous contact ellipse of tooth profiles is established and the equations of contact trajectory are also derived. The contact ellipse area of tooth surfaces of the gear pair with double contact points is solved by the numerical analysis method, and the influences of the design and tooth profiles parameters on the contact ellipse are discussed. Using the finite element analysis method, the contact ellipse area and tooth surface contact stress of the internal meshing gear pair with single contact point and double contact points are compared. The research conclusions show that the contact area location and size can be effectively controlled by selecting the suitable contact angle, nominal pressure angle, normal modulus and spiral angle. Under the same parameters, the contact area with double contact points is larger than that of a single contact point, and the contact stress is smaller. The relevant research has important theoretical significance and reference values for improving the contact characteristics and mechanical properties of the new internal meshing gear transmission.

The internal excitation of gear meshing transmission is the key factor that causes gear vibration and noise. Taking a pair of constant meshing helical gears in an 8-speed automatic transmission as the research object,the internal excitation of meshing transmission process is studied thoroughly,including the tooth surface contact state,time-varying meshing stiffness,error excitation and meshing impact. The finite element method is used to analyze the static and dynamic contact process of helical gears to get the magnitude and distribution of tooth contact stress. The change of contact line length is used to represent the time-varying meshing stiffness. The time-varying meshing stiffness of helical gear is obtained by theoretical analysis and finite-element simulation. Theoretical analysis and finite-element method are used to analyze the error excitation of helical gears,including the meshing error,the static transmission error and the dynamic transmission error. The finite-element method is used to analyze the meshing impact to obtain the root stress of gear transmission. The stress distribution on tooth contact line is calculated by the finite-element method. The above research lays the foundation for the improvement of helical gear transmission state.

In order to suppress the vibration in the end of large double-link hydraulic flexible manipulator,taking the heavy load hydraulic flexible mechanical arm as the study object and aiming at the end of arm movement in the process of vibration phenomenon,by the servo-hydraulic system-Euler Bernoulli model,Lagrange equation and Jacobian matrix,a piezoelectric feedback driven system control method is designed,through the end of the robot arm equipped with sensitive piezoelectric transmitter,piezoelectric actuators and inversion control design methods,the movement of servo hydraulic cylinder vibration,the hydraulic cylinder with manipulator friction and manipulator rod elastic vibration influence of the hydraulic flexible manipulator end vibration are studied. The simulation results show that,the vibration suppression method for better stability control,the end vibration of hydraulic flexible manipulator can be significantly reduced,the vibration attenuation time is shortened,the positioning precision can be improved obviously.

To study the influence of multi- floating components on the load sharing of heavy load planetary gear system,taking a large wind power planetary gear system as the research object. The FE model of this system is established to analyze the load sharing. The load sharing change trend of the planetary gear with the change of planet carrier stiffness,planet gear error and the floating of the sun gear and the planet carrier,external load are analyzed. The results demonstrate that the load sharing of the system is better in the case of the floating sun and planets gear carrier at the same time. Reducing the stiffness of the floating support or increasing input load can effectively improve the load sharing capacity. The experimental verification of load sharing situation of multi- floating component planetary gear system under the change of external load and planet carrier support stiffness is carried out on the load sharing test platform.

The Yangtze River Delta region is an important commodity grain production area in China, but has been suffering from agricultural non-point source pollution issues in recent years. This study puts forward a suggestion on promoting the construction of zero-direct discharge (ZDD) engineering for agricultural wastewater from paddy fields in the region. This suggestion is based on the field investigation, policy analysis, engineering design, and economical evaluation, which clarifies the policy adaptability and the construction importance of the ZDD engineering. At the same time, this suggestion shows the basic principles, design requirements, mode selections, investment cost, and expected ecological economic benefits of the ZDD engineering. It is expected to provide decision support for China to mitigate the non-point source pollution and enhance agricultural green development. [ABSTRACT FROM AUTHOR]

Adaption control strategy is a core technology as one part of control software for automatic transmission. The purpose of such strategy development is to compensate deviations due to engine torque signal difference, tolerance of transmission parts during manufacture, purchasing, storage and assembly processes, characteristics change with mileage accumulation, and to ensure acceptable shift quality and good drivability for the whole life of products. Many efforts have been made aimed to design self-learning strategies especially for dual-clutch automatic transmission and automated mechanical transmission by establishing vehicle launch strategy, feedback pressure control and solenoid duty cycle adjustment. While due to lack of pressure sensors in hydraulic automatic transmission, most of theories cannot be used directly. In overseas, main introductions on adaptive methods for upshift and downshift are published, but key technical information is strictly protected by corresponding patents and no detailed knowledge for instance control procedure is issued. According to different shift phases such as filling phase, torque phase and speeding phase, separated adaption methods like self-learning approach based on torque estimation or turbine acceleration signal are analyzed. But pressure sensor signal, longitudinal acceleration signal or high engine torque resolution are required for the application of those strategies, which seems not suitable for series transmission or low-level vehicles with domestic brands. To meet the requirements for TCU (transmission control unit) control software of vehicle production, adaption function for shifting clutches is researched, and corresponding software structure is introduced which includes shift type decision, shift quality monitoring, parameter adjustment and complicated method for adaption data update and storage. In addition, according to different profiles in torque phase and speeding phase for power on upshift and power on downshift, adaption strategies based on shifting time and turbine speed flare issue are proposed respectively. Then, according to shift sequence and shift control parameter of self-learning approach, complete software control procedures for parameter detection, processing, calculation and response are illustrated. It is very helpful for further research since parameter self-adjustment procedure turns to be clear with step by step introduction. A patent testing method is produced for recording shift issues, shift points, driving cycles and checking adaption results. The vehicle testing results showed that through adaption parameter adjustment, shifting time achieves to the target value, 700 ms, during power on upshift with only 2 repeated operations and for power on downshift, engine and turbine speed flare can be avoided gradually which makes shift quality better and more solid. The shift shock is reduced to 5 m/s3, which achieves to production vehicle shift quality level. The deviations due to the inconsistence of transmission from vehicle to vehicle and from engine to engine during manufacture and assembly process and characteristics deterioration can be compensated in very short time according to current research outcomes. [ABSTRACT FROM AUTHOR]

The clutch slip control in the shifting process of hydraulic automatic transmission covering oil filling phase, torque phase and synchronizing phase is analyzed in detail. During the 3 phases, through the closed loop control over the potential torque and oil pressure of clutch by using feed-forward PID control, the accurate desired clutch slip is obtained. In the synchronizing phase, the EMS-assisted torque control is adopted to achieve smoother speed synchronization and less shift shock. For easy calculation of clutch slip, a scheme of clutch position equivalent transfer is also proposed in this paper with the calculation formulae of conversion factor given. The results of vehicle test show that during the process of power-on up shift with clutch slip control, the engine torque transmission and clutch speed synchronization become smoother and the shift shock is reduced with a jerk value lower than 20m/s³. In addition the oil pressure sensors in clutches can also be eliminated for cost saving. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of Achyranthes bidentata polysaccharides (ABPS) on adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and its mechanism. Methods Five SD rats were sacrificed, and the BMSCs were dissected and isolated. The BMSCs were adherently cultured to logarithmic growth phase after identification, and treated with different doses of ABPS for 48 hours. The cell survival rates were detected by MTT assay. The highest dose of ABPS without toxicity to BMSCs was selected for subsequent experiments. Cells were randomly divided into control group, ABPS group, rosiglitazone group and ABPS combined with rosiglitazone group. Cell survival rates were detected by MTT assay. Triglyceride (TG) levels in BMSCs were detected by spectrophotometry. Lipid droplet formation in BMSCs was observed by oil red O staining. The mRNA and protein expression of peroxisome proliferater-activated receptor γ (PPARγ), transient receptor potential vanilloid 4 (TRPV4) and CCAAT/enhancer binding protein α (C/EBPα) were detected by real time quantitative PCR and Western blot analysis. Results The dose of ABPS≤200 mg/L had no obvious toxic effect on the growth of BMSCs after 48 hours, and the cell survival rate of 400 mg/L ABPS group was lower. Compared with the control group, the ABPS group showed decreased levels in TG, decreased relative expression of PPARγ, TRPV4 and C/EBPα mRNA and protein, and the decreased number of cytoplasmic lipid droplets. In the rosiglitazone group, observation reported the decreased cell survival rate, increased TG level, increased relative expression levels of PPARγ, TRPV4 and C/EBPα mRNA and protein, along with the increased number of cytoplasmic lipid droplets. Compared with the ABPS group, the cell survival rate was decreased, TG level was increased, the relative expression levels of PPARγ, TRPV4 and C/EBPα mRNA and protein increased, and the number of cytoplasmic lipid droplets increased in the ABPS combined with rosiglitazone group. Compared with rosiglitazone group, the survival rate was increased, TG level was decreased, the relative expression levels of PPARγ, TRPV4 and C/EBPα mRNA and protein were decreased, and the number of cytoplasmic lipid droplets was decreased in the ABPS combined with rosiglitazone group. Conclusion ABPS can inhibit adipogenic differentiation of BMSCs, and the mechanism may be related to the regulation of PPARγ/TRPV4 pathway.

Objective: To investigate the effectiveness of corrective osteotomy for shortened medial foot column after old talar neck fracture., Methods: The clinical data of 10 patients with shortened medial foot column after old talar neck fracture between June 2012 and May 2017 was retrospectively analyzed. There were 7 males and 3 females with an average age of 45.8 years (mean, 21-67 years). The time from fracture to corrective osteotomy was 9-60 months (mean, 20.9 months). The preoperative visual analogue scale (VAS) score was 7.1±1.2, the American Orthopaedic Foot and Ankle Society (AOFAS) score was 48.5±12.3, and the short-form 36 health survey scale (SF-36) score was 46.7±10.5. All 10 cases received open wedge osteotomy of medial talus. Among them, 2 received subtalar fusion and Achilles tendon lengthening, 2 lateralizing calcaneal osteotomy, and 2 Achilles tendon lengthening., Results: All incisions healed by first intention. All patients were followed up 13-72 months (mean, 38.0 months). The X-ray film showed that the angle between longitudinal axis of 1st metatarsal bone and talus increased from (-9.6±4.5) ° before operation to (1.3±2.7) ° at last follow-up ( t =16.717, P =0.000); the angle between longitudinal axis of calcaneus and tibia increased from (-12.0±7.4) ° before operation to (-1.5±4.8) ° at last follow-up ( t =5.711, P =0.000). At last follow-up, the VAS score, AOFAS score, and SF-36 score were 1.6±1.0, 88.3±5.4, and 85.4±9.2, respectively, which increased significantly when compared with the preoperative scores ( t =13.703, P =0.000; t =14.883, P =0.000; t =16.919, P =0.000). X-ray film and CT showed that the osteotomy and arthrodesis sites healed well at 2-4 months after operation., Conclusion: It's a proper procedure of anatomic reduction and reconstruction for patients with shortened medial foot column and good articular cartilage morphology after old talar fracture. Opening wedge osteotomy of medial talus is recommended and can obtain satisfactory clinical and radiographic results.

Objective: To explore the feasibility of the repair and reconstruction of large talar lesions with three-dimensional (3D) printed talar components by biomechanical test., Methods: Six cadaveric ankle specimens were used in this study and taken CT scan and reconstruction. Then, 3D printed talar component and osteotomy guide plate were designed and made. After the specimen was fixed on an Instron mechanical testing machine, a vertical pressure of 1 500 N was applied to the ankle when it was in different positions (neutral, 10° of dorsiflexion, and 14° of plantar flexion). The pressure-bearing area and pressure were measured and calculated. Then osteotomy on specimen was performed and 3D printed talar components were implanted. And the biomechanical test was performed again to compare the changes in pressure-bearing area and pressure., Results: Before the talar component implantation, the pressure-bearing area of the talus varied with the ankle position in the following order: 10° of dorsiflexion > neutral position > 14° of plantar flexion, showing significant differences between positions ( P <0.05). The pressure exerted on the talus varied in the following order: 10° of dorsiflexion < neutral position < 14° of plantar flexion, showing significant differences between positions ( P <0.05). The pressure-bearing area and pressure were not significantly different between before and after talar component implantations in the same position ( P >0.05). The pressure on the 3D printed talar component was not significantly different from the overall pressure on the talus ( P >0.05)., Conclusion: Application of the 3D printed talar component can achieve precise repair and reconstruction of the large talar lesion. The pressure on the repaired site don't change after operation, indicating the clinical feasibility of this approach.

Objective: To evaluate the effectiveness of interference screw and flexor hallucis longus tendon as augmentation material in repair of chronic Achilles tendon rupture., Methods: From October 2004 to June 2007, 32 patients (35 feet) with chronic Achilles tendon rupture were treated, including 21 males (22 feet) and 11 females (13 feet) and aging 32-85 years. The disease course was 4-132 days. There were 29 patients with hooflike movements history and 3 patients without obvious inducement. The result of Thompson test was positive in 31 cases (33 feet). The score was 56.09 +/- 7.25 according to the American Orthopaedic Foot and Ankle Society ankle-hindfoot scoring system (AOFAS). MRI indicated that the gap of the chronic Achilles tendon rupture was 0.5-5.0 cm. Medial foot incision associated with medial heel incision or only medial heel incision was made to harvest flexor hallucis longus tendon. The tendon should be 3 cm longer than the end of the Achilles tendon, then fix the tendon to the calcaneus., Results: Wound dehiscence occurred and wound healed after dressing change in 1 case; wound healed by first intention in other patients. Thirty-two patients were followed up for 12-32 months (mean 19.4 months). The AOFAS score was 94.22 +/- 4.63, showing statistically significant difference when compared with that before operation (P < 0.01). The results were excellent in 28 cases, good in 3 cases and fair in 1 case. No sural nerve injury, posterior tibial nerve injury, plantar painful scar, medial plantar nerve injury and lateral plantar nerve injury occurred., Conclusion: Flexor hallucis longus tendon transfer offers a desirable outcome in operative recovery, tendon fixation and complications.

The study showed that after inoculating 10 g x kg(-1) anaerobic dechlorinated granular sludge (ADGS) for 31 days, the biodegradation rate of pentachlorophenol (PCP) in solid-liquid phase of contaminated sediment slurry was up to 98.9%, with an average of 8.0 mg x kg(-1) x d(-1), while that of the control was only 4.4 mg x kg(-1) x d(-1). As the regulation factors in slurry remediation, organic solvent, co-substrate and surfactant had different effects on PCP degradation. The addition of ethanol could enhance the desorption and degradation of PCP, the degradation rate being up to 54.3 mg x kg(-1) d(-1) within 4 days, while the addition of co-substrate and non-ionic surfactant EGME (ethylene glycol monobutyl-ether) inhibited the PCP degradation in solid-liquid phase of slurry.

Objective: To establish the fingerprints of Achyranthes bidentata Bl. by HPLC/UV/MS., Method: Separation was performed on Aglient Zorbax SB-C18 column. Gradient elute was performed by the mobile phase consisting of methanol and 0.1% formic acid-water with the flow rate of 1.0 ml/min., Result: Perfect fingerprints were obtained which can be used for the evaluation of Achyranthes bidentata Bl. Four common peaks were confirmed in fingerprints. Three compounds were elucidated as 5-hydroxymethyl furaldehyde, ecdysterone, inokosterone by HPLC/MS., Conclusion: The method can be applied to the quality control of Achyranthes bidentata Bl.