Harbin Foresty Machinery Institute

A hospital-based case-control study of oesophageal cancer was carried out in the Heilongjiang Province, a low-risk area for oesophageal cancer in China. From May 1985 to May 1989, 196 histologically confirmed cases and 392 controls with other (non-neoplastic) diseases were personally interviewed in the wards of 5 major hospitals. Information was obtained about usual consumption in the early 1980s of 32 major contributors to the diet in the province, socio-demographic status, smoking and alcohol consumption. Odds ratios (OR) were obtained from logistic regression models, and confounding was controlled by means of multivariate models. Smoking and alcohol consumption were major risk factors for oesophageal cancer in this population. Smokers of handmade cigarettes exhibited a particularly high risk. A near multiplicative synergism was found between smoking and alcohol consumption. There was a significant inverse dose-risk trend for combined consumption of vegetables and fruits; a 300-g increase per day lowered risk by 35%. Vitamin C intake was negatively associated with risk; a 100-mg increase per day lowered risk by 39%. Our data suggest a modifying effect of vitamin C and beta-carotene on risk associated with smoking, but the power of analyses was low. Salt, salt-preserved foods and pickled vegetables were not associated with increased risk. High temperature of meals and drinks was a strong risk indicator in this population. The strength of tea and overall tea consumption were independent determinants of the risk.

Lexical embeddings can serve as useful representations for words for a variety of NLP tasks, but learning embeddings for phrases can be challenging. While separate embeddings are learned for each word, this is infeasible for every phrase. We construct phrase embeddings by learning how to compose word embeddings using features that capture phrase structure and context. We propose efficient unsupervised and task-specific learning objectives that scale our model to large datasets. We demonstrate improvements on both language modeling and several phrase semantic similarity tasks with various phrase lengths. We make the implementation of our model and the datasets available for general use.

Epoxy resin is widely used in electrical equipment and electronic devices fields due to its excellent electrical, thermal, and mechanical properties. However, its internal three-dimensional covalent interconnection structure brings barriers to its degradability and recycling because covalent bonds cannot be broken easily. With the replacements of power equipment and electronic devices, there will be more and more epoxy resins and their composites in them to be treated and effective recycling is of great significance for resource conservation and environmental protection. In this review article, recent progress in degradation and recycling of epoxy resin is introduced and the effect of three traditional degradation methods is discussed. The drawbacks of these methods are thought to come from the intrinsic properties of these epoxy resins. So the urgency of developing new kinds of degradable epoxy resins is proposed. Then different types of new degradable epoxy resins are reviewed. Degradation mechanisms of the opened-loop recycling and recycling methods of the closed-loop recycling are summarized in detail. Finally, the challenges and perspectives are discussed based on their current developments. This review comprehensively considers both traditional degradation methods and new methods for developing degradable epoxy resins. It covers not only an overview of the state-of-the-art advances of degradation and recycling of epoxy resin but also the prospects that provide reference for the synthesis of degradable epoxy resin materials.

Pumped hydro energy storage (PHES) is currently the only proven large-scale energy storage technology. Frequent changes between pump and turbine operations pose significant challenges in the design of a pump-turbine runner with high efficiency and stability, especially for ultrahigh-head reversible pump-turbine runners. In the present paper, a multiobjective optimization design system is used to develop an ultrahigh-head runner with good overall performance. An optimum configuration was selected from the optimization results. The effects of key design parameters—namely blade loading and blade lean—were then investigated in order to determine their effects on runner efficiency and cavitation characteristics. The paper highlights the guidelines for application of inverse design method to high-head reversible pump-turbine runners. Middle-loaded blade loading distribution on the hub, back-loaded distribution on the shroud, and large positive blade lean angle on the high pressure side are good for the improvement of runner power performance. The cavitation characteristic is mainly influenced by the blade loading distribution near the low pressure side, and large blade lean angles have a negative impact on runner cavitation characteristics.

We cloned a Cinnamoyl-CoA Reductase gene (BpCCR1) from an apical meristem and first internode of Betula platyphylla and characterized its functions in lignin biosynthesis, wood formation and tree growth through transgenic approaches. We generated overexpression and suppression transgenic lines and analyzed them in comparison with the wild-type in terms of lignin content, anatomical characteristics, height and biomass. We found that BpCCR1 overexpression could increase lignin content up to 14.6%, and its underexpression decreased lignin content by 6.3%. Surprisingly, modification of BpCCR1 expression led to conspicuous changes in wood characteristics, including xylem vessel number and arrangement, and secondary wall thickness. The growth of transgenic trees in terms of height was also significantly influenced by the modification of BpCCR1 genes. We discuss the functions of BpCCR1 in the context of a phylogenetic tree built with CCR genes from multiple species.

Similarities of the flow in the rotor–stator interaction (RSI) affected region (stay vanes, guide vanes, and runner domain) in prototype and model Francis pump-turbines are analyzed using numerical simulations with special attention on the influence of Reynolds number. The ratios of characteristic length and velocity between the prototype and the model are 10.97 and 2.54; thus, the Reynolds numbers differ by about 28 times. Detailed flow analysis argues for higher partial load condition, Q = 0.8Qd, and severe partial load condition, Q = 0.45Qd. The flows in the distributor (spiral casing, stay vanes, and guide vanes domain) are well-behaved for both conditions with no separation, presenting high level of similarity in both space and time domain. The flows in the runners are well-behaved at higher partial load, Q = 0.8Qd, and present good flow similarity and weak Reynolds number effects between the model and the prototype. At severe partial load, Q = 0.45Qd, flow separation develops on the blade pressure sides and partially blocks the runner passages, showing prominent flow discrepancy and stronger Reynolds number effects between the two turbines. For the prototype flow of high Reynolds number, viscous effects have a minor role and less momentum is lost in the boundary layer. Therefore, the flow deceleration is less severe and the emergence of separation is restrained, presenting spatially delayed separation and a less disorganized flow pattern in the prototype. Validated by the model tests and on-site measurements, pressure fluctuations recorded in the vaneless space show that the relative fluctuation amplitudes in the model are slightly higher than those in the prototype. Resorting to dimensionless analytical equations and simulation results, the deviation in pressure fluctuations is found out to be influenced by Reynolds number effects. The research provides an improved understanding of Reynolds number effects on the flow discrepancy and pressure fluctuation difference in the RSI-affected region, which will facilitate better estimations of performance from scale model to prototype.

Numerical simulations were performed to investigate pressure fluctuations in the S-shaped region of a pump-turbine model. Analyses focused on pressure fluctuations in the draft tube and in the gap between the guide vanes and runner. Calculations were made under six different operating conditions with a constant guide vane opening, and the best efficiency point, runaway point, and low-discharge point in the turbine brake zone were determined. The simulated results were compared with experimental measurements. In the draft tube, a twin vortex rope was observed. In the gap between the guide vanes and runner, a low frequency component was captured at both the runaway and low-discharge points in the turbine brake zone, which rotated at 65% of the runner frequency. This low frequency component was induced by the rotating stall phenomenon. At the runaway point, a single stall cell was found in the gap between the guide vanes and runner, while at the low-discharge point, four stall cells were observed.

Due to the large flow and high channel flow velocity, the control of flow of the axial flow pump is more difficult, compared with centrifugal water pump. The improvement of problems induced by pressure fluctuation and noise are much more challenging. A numerical simulation of the hydraulic characteristics of a high specific speed axial flow water pump is carried out, and the reliability of the numerical model is verified through model test. The influence of the impeller geometric change on the performance of the pump was discussed, by means of parametric design and compute with the pressure fluctuation as design objectives. Hydraulic characteristics were compared between the initial and optimised impeller. The numerical simulation results show that by controlling the flow velocity in the impeller channel to a symmetrical distribution, the stability of the internal flow of the water pump can be enhanced, and the hydraulic vibration of the water pump can be reduced, as well as the fluid-induced noise.

A fast two-step marker-controlled watershed image segmentation method in CIELAB color space is presented in this paper. We choose a number of seed points distributed nearly uniformly as the makers to perform the first marker watershed segmentation step, and obtain superpixels of the input image. These markers have the minimal gradient in a 3 ×3 neighborhood, which is able to avoid placing them at an edge and to reduce the chances of choosing a noise pixel. After superpixels segmentation, we do not adopt the traditional region merging strategies based on the different features of the adjacent regions, but cluster the superpixels in a 5-D space composed of Lab color vector and the position coordinates of the superpixels to resolve the over-segmentation problem, which saves a lot of computation time. Experiments on various types of images demonstrate that our algorithm is faster than many other segmentation algorithms and very suitable for real-time applications.

A method using coupled fields and circuit equations is presented to calculate the end-region magnetic field, the current distribution in stator winding strands, and the circulating losses of the stator winding in large turbogenerators. In the calculation, the nonuniform distribution of current density in the stator winding and the influence on the end-region magnetic field of the copper shield are considered. Finally, the effect of the transposed angle on the circulating losses is analyzed. The method is used to calculate the end-region magnetic field and the current of the stator winding strands in a two-pole 300-MW generator. Numerical results are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

To investigate the influence of different electric shield materials on the temperature distribution in the turbogenerator end region, a 330-MW water-hydrogen-hydrogen-cooled turbogenerator is considered in this paper. Mathematical and physical models of the three-dimensional (3-D) transient electromagnetic field in the turbogenerator end region are established. The magnetic density distribution and the losses of end parts are obtained with different electric shield materials. The loss values obtained from the 3-D transient electromagnetic field calculations with different electric shield materials are applied to the end parts as heat sources. Pressure and fluid velocity values from flow network calculations are applied to the end region as boundary conditions for the fluid and thermal coupling analysis. In addition, a 3-D fluid and thermal coupling model of the turbogenerator end region is established. The distributions of the surface heat transfer coefficient on the inner and outer surfaces of the electric shield are determined with different electric shield materials. Temperature distributions of the stator-end copper winding, finger plate, clamping plate, and electric shield in the turbogenerator end region are investigated with different electric shield materials. The calculated temperature results for the electric shield are compared with measured values, and the calculated results agree well with the measured values.

A method for the computation of the transient electromagnetic torque in turbogenerators is given in which the iron saturation and the relative motion of the rotor and stator are taken into account. This method is based on the finite-element computation using a dynamic model coupled with the equations of external electric circuits. To avoid the airgap mesh distortion caused by the movement of the rotor, moving boundaries are introduced in the airgap. An example is given that involves the computation of the distribution of transient magnetic field and the electromagnetic torque of a 200-MW turbo-generator following different types of sudden short-circuits. The computed results agree with the measurements very well.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

BACKGROUND: The application of minimally invasive interventional breast surgery is becoming more and more widespread. The accurate puncture of breast cancer needs to solve the problems of tissue deformation and target displacement. METHODS: In this study, we analysed the process of leech blood absorption and developed a robotic needle insertion method based on bionic technology to improve the accuracy of breast cancer diagnosis and treatment. Among them, the design purpose of the sucker manipulator is to adjust and fix the breast tissue. We use uncalibrated visual servo to control soft tissue deformation. RESULTS: We compare the puncture effect of bionic needle puncture robot and common needle puncture on breast prosthesis and in vitro tissue. Experimental data shows that, compared with ordinary needle insertion, the robotic needle insertion method based on bionic technology greatly reduces the targeting error. CONCLUSIONS: This method is expected to provide a safe and effective alternative to traditional puncture for breast cancer diagnosis and treatment.

A three-dimensional thermo-elasto-hydro-dynamic model for bidirectional thrust bearings used in pump-turbines taking into account the temperature-viscosity effect as well as thermal-elastic deformations in the pad and runner surface was set up. The finite difference method was employed to solve the thermo-hydro-dynamic model, and the thermal-elastic deformations in the pad and runner were obtained by the finite element software ANSYS11.0. The data transfer between the thermo-hydro-dynamic model and ANSYS11.0 was carried out automatically by an interface program. Laboratory test was performed on the Harbin Electric Machinery 3000 ton thrust bearing test rig. A detailed comparison between the experimental results and numerical predictions showed quite good overall agreement on the oil film thickness, pressure and temperature, which provided an evidence of validation of the three-dimensional thermo-elasto-hydro-dynamic model coupled with finite difference method and finite element method developed in this article.

Skeleton tracking based on multiple Kinects data fusion has been proved to have better accuracy and robustness than single Kinect. However, previous works did not consider the inconsistency of tracking accuracy in the tracking field of Kinect and the self-occlusion of human body in assembly operation, which are of vital importance to the fusion performance of the multiple Kinects data in assembly task simulation. In this work, we developed a multi-Kinect fusion algorithm to achieve robust full-body tracking in virtual reality (VR)-aided assembly simulation. Two reliability functions are first applied to evaluate the tracking confidences reflecting the impacts of the position-related error and the self-occlusion error on the tracked skeletons. Then, the tracking skeletons from multiple Kinects are fused based on weighted arithmetic average and generalized covariance intersection. To evaluate the tracking confidence, the ellipsoidal surface fitting was used to model the tracking accuracy distribution of Kinect, and the relations between the user-Kinect crossing angles and the influences of the self-occlusion on the tracking of different parts of body were studied. On the basis, the two reliability functions were developed. We implemented a prototype system leveraging six Kinects and applied the distributed computing in the system to improve the computing efficiency. Experiment results showed that the proposed algorithm has superior fusion performance compared to the peer works.

The accurate and fast calculation of circulating currents between strands for different transposition types is the important premise of the engineering design for stator bars in large turbo-generators. The air gap magnetic field partly enters into the stator slot, also generating circulating currents. However, there is a lack of fast simulation method for calculating the air gap magnetic field entering the stator slot in the existing calculation method for circulating currents. In this paper, the analytical algorithm of calculating circulating currents considering the air gap magnetic field entering stator slots is proposed, in which the equivalent circuit model of transposed strands in stator bars is established based on the superposition principle, the analytical algorithm of calculating the induced electromotive force is proposed based on the discrete integral method, and the analytical algorithm of calculating the air gap magnetic field entering stator slots is proposed based on the conformal mapping method. Then, a 1400-MW turbo-generator is taken as an example, circulating currents between transposed strands in stator bars under no-load and rated condition are calculated by the proposed analytical algorithm. Finally, the proposed analytical algorithm is validated by the two-dimensional finite element method.

Bismaleimide (BMI) resin has great potential in aerospace, electronic, and machinery fields due to its extraordinary thermal stability. Owing to BMI’s lower impact strength, various modified BMI resins have been prepared using CTBN, PEEK, fillers, and hyperbranched polymer to achieve higher impact strength. However, enhancement of toughness causes deterioration of other performance, such as Tg, thermal stability, and brittleness. In this work, BMI resin modified by hyperbranched polyimide (HBPI) was obtained. HBPI designed with flexible segments, unsaturated bonds, and a low degree of branching was synthesized. FT-IR and 13C-NMR were applied to confirm the successful fabrication of HBPI. The mechanical strength and dielectric properties of cured BMI resin containing various levels of HBPI were analyzed systematically. The impact and bending strength were improved significantly with increased HBPI content. When the content of HBPI is 40 wt.%, the impact strength and bending strength reach the maximum value of 32 kJ/mm and 88 MPa. In addition, the BMI cured with HBPI exhibits enhanced bending modulus to the value of 5.9 GPa. Furthermore, the dielectric strength of cured resin was improved to 28.3 kV/mm. The improved mechanical strength and enhanced dielectric properties are attributed to the increasing free volume induced by HBPI. These results indicate the promise of BMI resin modified by HBPI applied in insulating coatings and low dielectric laminates used in high frequency.

Abstract Virtual reality (VR) has been proved as a promising tool for industrial design, but the traditional VR interface of first-person perspective (1PP) is not efficient to support assemblability assessment in narrow assembly spaces. In this paper, we proposed the multi-perspectives interface (MPI) which integrates the 1PP and the third-person perspective (3PP) using the handheld world-in-miniature (WIM). The MPI allows users to simulate the assembly operations in a natural manner similar to 1PP, while providing users with an overview of the assembly status through the WIM to assess the assemblability with superior spatial awareness. Two studies were conducted to test the performance of the proposed MPI. The first study tested user’s interaction performance in MPI using a common interaction task, which reveals stronger spatial awareness in MPI than in 1PP without the cost of losing natural interaction. Based on the results of the first study, the second study tested the performance, usability, and workload of MPI in an assemblability assessment task. The results show the advantages of MPI in the reachability evaluation in the narrow spaces. The main contribution of this paper is improving the interface and user-interface interaction in VR-aided assembly assessment system to improve user’s interaction performance and assessment ability in narrow assembly spaces.

By a controllable and stepwise strategy, a soluble ladder-conjugated perylene derivative BPI-FBI as the only product has been synthesized, which avoids the tough work to isolate regioisomers generated by a conventional one-step condensation method. BPI-FBI exhibits broad absorption spectra covering the whole visible region from 300 to 700 nm because of the large π-conjugation skeleton and has a low LUMO level inheriting the prototype PDI. In the steady-state space-charge-limited current (SCLC) devices, BPI-FBI exhibits an intrinsic electron mobility of 1.01 × 10(-5) cm(2) V(-1) s(-1). With a high two photon absorbing activity in the near-infrared region from 1200 to 1400 nm, BPI-FBI also exhibits good optical limiting performance, which will be useful for sensor or human eye protection and stabilization of light sources for optical communications.

Taking the S823 airfoil as the research object, this study investigates the influence of different types of leading-edge erosion on the aerodynamic performance of airfoil by using the computational fluid dynamics method. The effect of leading-edge erosion on the inception of stall vortex is also analysed. The results show that when the angle of attack (AoA) is greater than 5°, the leading-edge erosion results in a significant decrease in the lift coefficient and an increase in the drag coefficient. The deterioration in the drag coefficient of the airfoil caused by leading-edge erosion is much greater than that of the lift coefficient. Moreover, the maximum promotion rate of the drag coefficient can reach 357% at Re = 300,000. The exacerbation of the erosion level leads to a dramatic expansion of the stall vortex on the airfoil suction side at a large AoA and results in a reduction in the pressure difference between the pressure and suction sides of the airfoil. This is also the reason erosion causes the degradation of the aerodynamic performance of the wind turbine airfoil. This work is beneficial to establish the reasonable maintenance cycle of the wind turbine blades working in a sand blown environment.