- 高强;刘凡茜子;王科琴;周梦婕;郎晨宏;关福旺;崔丽娜;曾泳春;邱夷平;
Flax and jute fabrics are adopted to reinforce epoxy matrix composites in order to explore the feasibility of replacing wood in percussion instruments. The fabrics are treated with alkaline solutions to improve interfacial adhesion between fibers and epoxy. The composites are fabricated using the hand-lay and vacuum assisted resin infusion process. Acoustic dynamic moduli, acoustic radiation damping coefficients, and acoustic impedances of the composites are tested and compared with those of the wood regularly used to make the percussion instruments. It is found that the acoustic properties of the composites are within the range of those of the wood, indicating that it could be feasible to replace the wood with natural cellulose fiber reinforced composites in percussion instrument production.
2020年02期 v.37 91-95页 [查看摘要][在线阅读][下载 74188K] [网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：8 ] |[下载次数：101 ] - 李婷;李乔;
Yarn-based strain sensors serve as essential elements for wearable electronics in the applications of personal health monitoring, motion detection, and smart garments. In the paper, a yarn-based strain sensor was created by coating conductive polymer, polypyrrole(PPy), onto a double covered elastic yarn, i.e., polyurethane/polyamide/polyamide(PU/PA/PA) yarn. Surface morphology of the yarn-based strain sensors demonstrates that the PPy conductive particles are evenly distributed on the surface of the PA multi-filaments as well as immersed into the PU core. Cyclic tensile test is conducted to characterize the electro-mechanical performance of the yarn-based strain sensor. The mechanical hysteresis of the sensor is low, which mainly comes from the geometrical change of the PA filaments around the PU core. However, the electro-mechanical hysteresis of the sensor is large mainly due to the unrecoverable cracks of the PPy layers on the PU core.
2020年02期 v.37 96-100页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：9 ] |[下载次数：35 ] - 高雯;杨帆;
C/C-SiC composites have the potentiality to be applied in shield pumps of nuclear reactors as the bearing material because of their low density, good mechanical properties and excellent tribological properties. The C/C-SiC composites are fabricated via reactive melt infiltration(RMI) using silicon liquid infiltrated in C/C matrix composites. Friction and wear behaviors of C/C-SiC composites under water lubricated conditions are investigated using the block-on-ring test at room temperature, and compared with those of the resin graphite which is used as the bearing material in shield pumps at present. In addition, friction and wear mechanisms of C/C-SiC composites under water lubricated conditions have been discussed. Results show that tensile strengths of C/C-SiC composites are 150-210 MPa, and compressive strengths are 403-536 MPa. Friction and wear behaviors of C/C-SiC composites are closely related to the load and the speed. The time to reach a stable friction status decreases with the increase of the speed. Though the friction coefficient of C/C-SiC composites under water lubricated conditions is slightly higher than that of graphite, the wear rate of C/C-SiC composites is much lower, which suggests that the C/C-SiC composites can sustain a longer life during operation.
2020年02期 v.37 101-107页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：6 ] |[下载次数：31 ] - 李静;于海滨;崔丽娜;张锐;邱夷平;
Plantar pressure distribution of the designed cushioned soles was studied and compared with that of the commercially available sport shoes. A three-dimensional motion measurement system was used to obtain the peak plantar force, the peak plantar pressure, force-time integrals and pressure-time integrals, and one-way analysis of variance was used to analyze the performance of the designed cushioned shoes. The results revealed that in normal walking and jogging states, compared with the commercially available sport shoes, the peak plantar pressure in the heel region decreased by 13.65% and 6.05%, respectively. The peak plantar force decreased by 15.98% and 15.32%, respectively. The force-time integral decreased by 4.36% and 6.83%, respectively, and the pressure-time integral decreased by 10.58% and 11.00%, respectively. In conclusion, the cushioning performance of shoes is related to the exercise mode. For normal walking, the designed cushioned soles absorbed greater impact in the heel region, which was effectively cushioned, whereas in the jogging state, the designed cushioned soles exhibited a favorable cushioning effect in the forefoot region. The designed cushioned soles exhibited cushioning performance through the coupling design of material and structure, which effectively reduced impact force when landing and could optimize plantar pressure distribution.
2020年02期 v.37 108-115页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：8 ] |[下载次数：63 ] - 杨成飞;高东杰;何吉欢;
Nano or micro-scale particles are considered as a zero-dimensional material, and their shape is difficult to control. Here the crystal-like microparticles are formed, and the existence criterion of crystal-like low dimensional materials is established. The hydrothermal method is used to fabricate copper-1,3,5-phenyltricarboxylate(Cu-BTC) microparticles, which have a regular geometric shape with regular triangle, quadrangle and hexagon. The benzene ring and carboxyls(—COOH) attached to the benzene ring form two basic molecular structures of [Cu_3(BTC)_2]_n, which play an essential role in the construction of a three-dimensional crystal-like structure.
2020年02期 v.37 116-120页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：9 ] |[下载次数：74 ] - 印峰;陈新雨;邱杰;康永亮;
Boundary equilibrium generative adversarial networks(BEGANs) are the improved version of generative adversarial networks(GANs). In this paper, an improved BEGAN with a skip-connection technique in the generator and the discriminator is proposed. Moreover, an alternative time-scale update rule is adopted to balance the learning rate of the generator and the discriminator. Finally, the performance of the proposed method is quantitatively evaluated by Fréchet inception distance(FID) and inception score(IS). The test results show that the performance of the proposed method is better than that of the original BEGAN.
2020年02期 v.37 121-129页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：9 ] |[下载次数：44 ] - 周迦南;黄磊;徐世鹏;
A finite element method(FEM) is proposed to solve second elliptic problems posted in domains with rough boundaries. We also present an FEM for elliptic problems as an extension of the original method. The optimal error estimates in the energy norm are also proved. Numerical results for second elliptic equations in regular and rough domains are presented to illustrate the efficiency of our method, respectively, which is consistent with theoretical analysis.
2020年02期 v.37 130-136页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：5 ] |[下载次数：35 ] - 修国众;时宝;钱峰;
A scheme for optimal control problem formulation of a class of nonviscously damped system using pseudo-state-space formulation is presented in this paper. Taking the exponentially damped system of nonviscously damped system as an example, a new state space representation is applied to the n-order exponentially damped system. The necessary conditions for the optimality of the exponentially damped system are obtained. A numerical example of a single degree of freedom exponentially damped system is considered to illustrate the methodology and technique.
2020年02期 v.37 137-142页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：1 ] |[引用频次：0 ] |[阅读次数：7 ] |[下载次数：22 ] - 徐晓;周伟;褚童;
The symmetric dynamical model of a Cournot duopoly based on conjectural variation is established. Local stability of the equilibrium point is analyzed and the invariant sets are given. Then, dynamic behavior is studied by numerical simulation. With the change of gradient adjustment parameters, the routes to chaos vary. Synchronization occurs along the invariant sets accompanied by the on-off intermittency through the analysis of transverse stability. Coexistence of multiple attractors and structure of basins of attraction being more complex indicate more complicated bifurcation phenomena.
2020年02期 v.37 143-149页 [查看摘要][在线阅读][下载 11535K] [网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：8 ] |[下载次数：48 ] - 李生鹏;张顺;姚洪宇;曹士保;赵冰;
It is difficult to predict wind speed series accurately due to the instability and randomness of the wind speed series. In order to predict wind speed, authors propose a hybrid model which combines the wavelet transform technique(WTT), the exponential smoothing(ES) method and the back propagation neural network(BPNN), and is termed as WTT-ES-BPNN. Firstly, WTT is applied to the raw wind speed series for removing the useless information. Secondly, the hybrid model integrating the ES method and the BPNN is used to forecast the de-noising data. Finally, the prediction of raw wind speed series is caught. Real data sets of daily mean wind speed in Hebei Province are used to evaluate the forecasting accuracy of the proposed model. Numerical results indicate that the WTT-ES-BPNN is an effective way to improve the accuracy of wind speed prediction.
2020年02期 v.37 150-155页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：8 ] |[下载次数：20 ] - 王志宏;李悦;李红果;
Under partial trade credit, suppliers usually require retailers to pay a fraction of the purchase cost immediately when ordering and the remaining payment is deferred at the end of the sales period. Considering a supply chain consisting of a risk-neutral supplier and multiple loss-averse retailers, we develop models under partial trade credit. We analyze the optimal decisions of a supplier and retailers under decentralized decision-making. The study shows that there is a unique Nash equilibrium among the retailers, and the optimal total order quantity of retailers increases as the delayed payment ratio increases and as the degree of retailers' competition increases, but decreases with an increase in the loss aversion. Numerical studies are conducted to demonstrate the solution procedures and the effects of the parameters on decisions and profits.
2020年02期 v.37 156-162页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：8 ] |[下载次数：35 ] - 张明玉;
Student selection is of crucial importance for supervisors who are choosing students for postgraduate studies or research projects. Due to the challenge of asymmetric information, it is difficult for them to find suitable candidates. The existing methods do not work so well in the web 2.0 context which is inundated with vast online information. In order to overcome the deficiency, a research social network enhanced approach is proposed to provide decision support. It appeals to supervisors to adopt the proposed user-driven social marketing strategy. Meanwhile, this study mainly presents a system-driven personalized recommendation approach to support supervisors' decisions of student selection. The proposed method distinguishes supervisors based on their co-author networks to extract their potential preferences of collaboration styles. Subsequently, corresponding recommendation strategies are employed to provide personalized student recommendation services for targeted supervisors. A prototype is implemented on ScholarMate which provides online communication channels for researchers. A user study is conducted to verify the effectiveness of the proposed approach. The results enlighten designers to consider the differences among different users when designing recommendation strategies.
2020年02期 v.37 163-172页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：8 ] |[下载次数：59 ] - 王璐;赵晓康;
With the rapid development of China's economy, more and more listed companies have to face frequent corporate litigation. As corporate lawsuits are on the rise, it is necessary to study the measures taken by the company when a corporate litigation occurs. Some scholars' research indicates that top executive turnover may be one of the countermeasures, but few scholars have discussed this issue in the Chinese market. Our research uses 13 435 samples of Chinese market, takes the company's reputation as an observing point, and studies the relationship between corporate litigation and top executive turnover. In addition, due to the special political environment and the large differences in the legal environment between different provinces in China, we have further explored the moderating role of political conditions and legal conditions. It is worth mentioning that our empirical research method is the propensity score matching(PSM), and by this way we can easily avoid sample selectivity bias. Finally, a robust experimental conclusion is obtained: corporate litigation and top executive turnover are significantly positively correlated, and this correlation will be adjusted by political and legal conditions. Our research enriches the field of corporate litigation and also have certain guiding significance for the social construction of the rule of law in China.
2020年02期 v.37 173-180页 [查看摘要][在线阅读][下载 75829K] [网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：9 ] |[下载次数：26 ] 下载本期数据