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Based on the 3-UU parallel mechanism, a prototype robot for wrist joint rehabilitation is developed to assist stroke patients in wrist joint rehabilitation training. Based on the constraint relation and geometric characteristics of the 3-UU mechanism, the inverse kinematics of 3-UU mechanism is analyzed by spherical coordinate method and roll-pitch-yaw (RPY) method， and the relation between the platform and the driver is obtained. Compared with the classic 3-RRR wrist joint rehabilitation mechanism, the developed prototype has no advantages such as multi-solution and singular value. The motion performance of the prototype and the electromyographic signals of the two major muscle groups in the forearm are measured. The experimental results show that the maximum roll angle is -90° to 90°, the pitch angle is -90° to 90°， and the virtual yaw angle is -180° to 180°. The maximum electromyogram (EMG) signal can be generated at 950 mV. The results show that the developed model can meet the requirements of the wrist motion and train the forearm muscle group.

Abstract Before a wide range of enhanced oil recovery (EOR) techniques were implemented for an oilfield, the EOR potential and economic evaluation of the techniques should be evaluated in advance for each reservoir to determine which EOR technique was proper. In an oilfield developed with fluvial delta reservoirs, the complicated distribution of scattered small reservoirs in vertical and horizontal directions brought trouble for evaluation work. A rapid and reliable evaluation model for EOR techniques applicability was necessary to deal with the evaluation simulation for many small reservoirs of an oilfield. Combining fraction theory model with auxiliary equations, which describe the effect of formation heterogeneity and mechanism of different EOR technique on fractional flow rate, an evaluation analysis method for EOR techniques applicability of gas flooding, foam flooding and surfactant flooding was proposed. In the gas flooding model, the minimum miscible pressure of impure gas was introduced, and the relative permeability was modified by the minimum miscible factor. In the foam flooding model, changes in the mobility ratio and chemical adsorption were considered and a reduction factor of mobility ratio was introduced. In the surfactant flooding model, calculation formulas of viscosity and interfacial tension as well as the relative permeability were introduced. Finally, the model was simulated for a low permeability reservoir, and the simulation results were compared with that from Eclipse software. The similar results, little calculation time and feasibility of predicting optimal injection parameter had shown the reliability of the rapid evaluation model.

The long noncoding RNA DARS-AS1 was aberrantly expressed and participated in several human cancer progressions, whereas whether DARS-AS1 is involved in human gastric cancer remains unclear. This study aimed to investigate the influence of DARS-AS1 on gastric cancer progression and explore the potential regulatory network of DARS-AS1/miR-330-3p/NAT10. The expression levels of DARS-AS1, miR-330-3p, and NAT10 were measured by quantitative real-time polymerase chain reaction. The CCK-8 assay and Transwell assay were used to determine the cell viability, migration, and invasion capacities, respectively. The target association between miR-330-3p and DARS-AS1 or NAT10 was confirmed using a luciferase reporter assay. In result, DARS-AS1 levels were elevated in tumor tissues and associated with shorter overall survival in patients with gastric cancer. Knockdown of DARS-AS1 could hamper cell viability, migration, and invasion in gastric cancer cells. DARS-AS1 acts as a competitive endogenous RNA to regulate the NAT10 expression by sponging miR-330-3p in gastric cancer cells. In conclusion, DARS-AS1 was elevated in gastric cancer, and DARS-AS1/miR-330-3p/NAT10 signaling offered some new horizons for predicting prognosis and a novel therapeutic method for the treatment of gastric cancer.

[Objectives] In the structural design of composite wing-in-ground (WIG) craft, there is no standard way to evaluate the strength and stability of the structure. In this paper,the calculation methods for the structural strength and stability of the composite sandwich main float and wing of composite WIG craft are studied.[Methods] The theoretical methods for evaluating the structural design load of the main float and wing structure along with the corresponding strength criteria for sandwich panel are particularly discussed,as well as methods and criteria for the general and local stability of the sandwich panel. The overall longitudinal bending strength of the main float,structural strength of the composite sandwich wing, and their general and local stability are predicted and analyzed using the proposed method.[Results] The results show that the proposed method can be used for the strength and stability analysis of the main float and wing of composite WIG craft,and the composite WIG design scheme in the calculation example meets the structural strength and stability requirements,which is then verified by a real ship test.[Conclusions] This method can provide references for the design and structural analysis of composite WIG craft.

Nowadays, the full ocean depth submersible has become a focus of world marine research, and higher requirements are proposed for the mechanical properties of the pressure hull, the core component of a submersible, in the deep-sea environment. Upgrading the materials is one of the key ways to realize this goal. Due to such superior material properties as high specific strength and corrosion resistance, certain non-metallic materials such as composites, ceramics, glass, etc. are especially suitable for the manufacture of marine equipment, and show great potential for application to the pressure hull. This paper discusses the material requirements of deep-sea submersible pressure hulls, analyzes the advantages of composites, ceramics and glass in their material properties, briefly introduces the global development and application of various non-metallic materials in submersible pressure hulls, summarizes the technical problems currently faced and discusses avenues which deserve further study in this field.

Stress concentration caused by holes in a component is always an important research topic in structural safety assessment. Many studies have been carried out on linear elastic materials under static loading,including the effects of hole shape,material anisotropy and loading direction on stress concentration. However,the coupling effect of the nonlinear stressstrain relationship and the strain-rate effect will lead to a great difference between the stress concentration for the plastic material and the existing linear elastic results when the material is under dynamic loading,especially for many kinds of metal materials with plastic deformation. Therefore,based on the Johnson-Cook model,the stress concentration at the hole root of a typical 45 steel plate under dynamic loading is systematically analyzed using finite element method. The results show that the plastic stress concentration factor depends not only on the loading magnitude（ strain） but also on the loading speed（ strain rate）. For the plate at plane stress state under the remote strain of 1%,the stress concentration factor at the circle hole for ε∞= 20/s is around 10%higher than that for ε∞= 0. 1/s,while the stress concentration factor at the elliptic hole with the shape factor（ minor axis/major axis） of 0. 5 for ε∞= 20/s is around 11% higher than that for ε∞= 0. 1/s.

With the development of semiconductor technology, characteristic frequency of transistors have been improving so far and into THz frequency range, which makes it possible for solid state devices to work in THz frequency range. THz amplifier plays a key role in THz system because of its function amplifying weak THz signals. This paper introduces the latest research progress of THz monolithic amplifier based on Gallium Nitride(GaN) High Electron Mobility Transistor(HEMT)，Indium Phosphide(InP) HEMT and InP Heterojunction Bipolar Transistor/Double Heterojunction Bipolar Transistor(HBT/DHBT).

In this paper, graphene oxide (GO) was modified with alkyl amidopropyl diethanolamine to obtain a nano pour point depressant (GO-PPD), which was used to improve the flowability of the waxy oil extracted from Changqing Oilfield, China. Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), polarized optical microscopy (POM) and viscometer were employed to evaluate the performance of the GOPPD. The results showed that compared with traditional pour point depressant (PPD), the GO-PPD exhibited higher performance in promoting the flowability of waxy crude oil. With the presence of 500 mg/kg GO-PPD in the waxy crude oil, the pour point of which could be reduced by 5.5 °C. Also, with the presence of 500 mg/kg GO-PPD, the viscosity reduction rate of the waxy crude oil can reach up to 52% at 30 °C. Through the observation via polarized microscopy, we have also found that with the introduction of GO-PPD in the crude oil, the formation of the wax crystals can be greatly retarded. This confirmed that the graphene oxide derivates could also be served as PPD, which facilitates the flowability of certain crude oil (e.g., waxy crude oil from Changqing Oilfield).