bluuebunny/crossref_metadata_2025 huggingface dataset:
Ownerships Structures and Accounting Conservatism among Nigeria Listed Firms
Authors: Asiriuwa O , Akperi R T , Uwuigbe O R , Uwuigbe U , Nassar L , Ilogho S , Eriabe S
Published: October 2019

The article aims to examine the effect of ownership structure on accounting conservatism among Nigeria listed firms. Correlational research design was employed in this study and the sample size comprises of all 15 firms from the banking sector listed on the Nigerian Stock Exchange (NSE) for the years 2013 – 2017. The study employed the panel regression technique to estimate the coefficients of the variables in the model specified.

The study finds that there is a positive and insignificant relationship between managerial ownership and accounting conservatism; a positive but an insignificant relationship was observed between institutional ownership and accounting conservatism. However, foreign ownership revealed a negative but not significant relationship with accounting conservatism. We recommend that financial statements to include more detailed analysis of the structure of their ownership and shareholding to provide more information for decision making for users of the accounting information such as researchers and potential investors. Also, Regulatory bodies should ensure all companies comply with the concept of conservatism by imposing strict penalty on erring companies.
On the need for the development of low wind speed turbine generator system
Authors: Ajayi Oluseyi O. , Ojo Olorunfemi , Vasel Ahmed
Published: October 2019

The study focused on the need for the development of a low cut-in wind speed turbine system with a view to challenge for concerted efforts towards improvement in design in such a way that favours operation at wind speeds as low as 1.5 to 2.0 m/s. It reviewed some existing reports on rotor designs with major focus on improved blade design for enhanced turbine performance and structural integrity. It found that despite the advances in turbine blade designs, there is the need to further the design to include those that can drive generators not just for small wind turbine applications but also for operation under lower cut-in speeds (less than 2.0 m/s). It further demonstrated the need to have improvement in wind turbine generator design that eliminates/reduce lubrication parts and possibly employ electro-magneto-mechanical principles for operation.
Corporate ethical standard and the quality of sustainability reporting: empirical evidence from commercial banks in nigeria
Authors: Oluseyi-sowunmi Sharon O , Owolabi Akintola A , Iyoha Francis O , Uwuigbe Olubukola R
Published: October 2019

Compliance with legal requirements is mandatory for corporate entities in Nigeria, but decision making in a situation that is not legally binding relies on the ethical standard of the company. Sustainability reporting in Nigeria is voluntary, therefore the quality of disclosure is at the discretion of company leadership. This study evaluated the ethical behaviour of Nigerian commercial banks and how it affects their sustainability disclosure quality. The Focus was on the proportion of each bank’s corporate annual reports that contain environmental disclosure, social responsibility disclosure and governance disclosure. Information on the banks’ websites that relate to sustainability policies or activities were also considered. This work includes an extensive review of relevant literature, hinging the study on legitimacy theory. The Cross-sectional research design was utilized in undertaking the study. A sample of fourteen (14) commercial banks was selected from the companies listed on the Nigerian stock exchange and analysed for a period of 2008-2017 financial years. Pearson Correlation and Multivariate Linear model analysis were employed to test the hypotheses. Findings revealed a positive relationship between corporate ethical standard and sustainability disclosure of Nigerian commercial banks. The level of corporate ethical standard in Nigerian banks causes significant positive change in environmental reporting quality, social responsibility reporting quality and governance reporting quality. It is hereby, recommended that company leadership should build strong corporate ethical culture since it directly affects their sustainability. While quality sustainability reporting practice is beneficial to the reporting entity, stakeholders and environment.
Preface
Authors: Zou Bin
Published: October 2019

The Second International Workshop on Environment and Geoscience (IWEG2019) was successfully held in Hangzhou, China during July 17-19, 2019. The conference was an annual forum for researchers and application developers in the area of environment and geoscience.

This conference proceeding included 50 accepted articles selected from 107 submissions.

We would like to express our gratitude to the reviewers of these manuscripts, who provided constructive criticism and stimulated comments and suggestions to the authors. We are extremely grateful as organizers, technical program committee and editors and extend our most sincere thanks to all the authors for their excellent contribution and work. Our sincere gratitude also goes to the IOP Publishing editors and managers for their helpful cooperation during the preparation of the proceeding.

On behalf of the Organizing Committees of IWEG2019

Photos of IWEG2019 are available in the pdf.
Study on early warning mechanism of ecological water safety in typical watershed of arid areas
Authors: Wei Qing , Xue Lianqing , Wei Guanghui , Liao Shumin , Fu Fangbing
Published: October 2019

In order to improve the comprehensive management level of water resources in the Tarim river basin, a regional water ecological security early warning indicator system were established. Combining the Analytic Hierarchy Process (AHP) and the Fuzzy Comprehensive Evaluation (FCE), the complex adaptive mechanism of the water security system was integrated. The watershed overall water security belongs to safer status. Regional water security status showed a certain difference, and overall decreased gradually from west to east. Secondary indicators also different in time and space scale, and showed the geographical consistency. While Aksu and Bazhou were in a slight warning status, and regional water resources development level was moderate. Therefore, the regional economic development and water use efficiency should be enhanced to ensure water safety of the basin.
Characteristics analysis of the reservoir landslides base on unmanned aerial vehicle (UAV) scanning technology at the Maoergai Hydropower Station, Southwest China
Authors: Yang Yuchuan , Wang Xiaobo , Jin Wei , Cao Jiayun , Cheng Baogen , MaosenXiong  , Zhou Shunwen , ChaoZhang
Published: October 2019

With the development of unmanned aerial vehicle (UAV) technology, UAV scanning technology has been applied widely in the world. However, the application of UAV is not sufficient in the current geotechnical engineering due to its high cost. The paper analyzed landslide characteristics of the Maoergai reservoir base on a small UAV. With the help of Pix4D, the image data collected by UAV can be processed into a three-dimensional terrain. And then the characteristics including landslide scale, landslide elevation, average slope can be obtained by use of Google Earth software. Analysis results reveal that the occurrence frequency of landslides is very high, and the most prone to triggering reservoir landslide elevation is about 2150m∼2199m. In addition, 30° to 35° is the major slope range that reservoir landslides occurred. Water fluctuation (rising or drawdown of the water level) played a key role in triggering Maoergai reservoir landslides. The potential initiation mechanism of a reservoir landslide due to the fluctuation of water level was discussed in the paper. Through the application in the hydropower engineering, the paper provided some ideas for the further development of UAV scanning technology.
Remote sensing imaging: a useful method for assessing wetland vegetation evolution processes in the Nanjishan Wetland National Nature Reserve, Lake Poyang
Authors: Zhang Jie , Li Jing , Wang Xueru , Wu Peijun , Liu Xingchen , Ji Yong
Published: October 2019

To obtain authentic details on wetland vegetation distribution and evolution processes, remote sensing images were used to calculate the vegetation area of the Nanjishan Wetland National Nature Reserve (NWNNR) in wet (flooding) and dry seasons. The results showed that the vegetation coverage areas were significantly negatively correlated with the water levels. Moreover, the vegetation coverage areas in the dry season presented an obvious decreasing trend since 2008 when the Three Gorges Dam (TGD) began operations, whereas the vegetation areas in the flooding season significantly increased. A statistical analysis indicated that significant differences occurred in the vegetation areas before and after 2008 in both the flooding and dry seasons. Furthermore, the vegetation distribution regions also changed in the same period over different years. Obvious regional variations were not observed in the flooding season due to the lower vegetation coverage areas. However, the spatial distribution of vegetation in the dry season showed a mix of river, lake and beach regions, which indicated the fertility of the soil for wetland vegetation to grow and develop. From 1995 to 2008, the vegetation distribution area was mainly located in the southwest of the NWNNR. Since 2009, the vegetation distribution in the northeast area has been dominant in the dry season compared with the aggregation in the southwest. The influence of human behavior, extreme climate change and water conservancy project construction had an important influence on the distribution and evolution of wetland vegetation in the NWNNR.
Temporal-spatial variation atlas analysis of land use: A case study from Yiyang City, Hunan Province, China
Authors: Xue Yun , Tang Fanghua , Liu Shishi , Liu Jianglong , Sun Yurong
Published: October 2019

The paper finished the land use time series changes atlas analysis, spatial series changes atlas analysis and the fluctuation potential map analysis of Yiyang city by using the land use data in 2005, 2010 and 2014. The results show that: (1) during the period from 2005 to 2014, the land use situation in Yiyang changed greatly, the area of construction land and water continued to increase, the garden area was decreasing, the area of cultivated land increased first and then decreased, meanwhile the area of woodland first decreased and then increased, and the area of cultivated land and woodland decreased as a whole. In the newly added area, the cultivated area rose the strongest, followed by woodland and water. In the shrinking area, the woodland area decreased most significantly, followed by cultivated land and the construction land area transfer rate was relatively low. (2) On the land use change amplitude and velocity view, the most obvious growth type of land use in Yiyang is construction land, and the scale of construction land expansion in Anhua County is relatively large. Then followed by water area, in which the maximum growth rate is in Heshan District and the next is in Anhua County. The other types of land use were all reduced.(3) From the analysis of relative change rate of land use type, the regional difference of land use type change in Yiyang is remarkable. In the last ten years, the biggest increasing range of construction land and cultivated land is in Anhua County relative to the whole city, and the biggest garden land increasing rate appears in Nanxian County. There is relatively great difference in forest land increasing rate, the biggest rate appears in Ziyang District, The difference in relative rates of change in waters is small, except the Heshan District and Anhua County have relative large variations, the changes in other parts of water with the relatively consistent.
Application of Tebeca soil conditioner can increase vegetable yield and reduce heavy metal accumulation in red soil region
Authors: Huang Dongfeng , Pan Zhucai , Qiu Xiaoxuan
Published: October 2019

A field plot trial was conducted to study the effects of applying different dosages of Tebeca soil conditioning (i.e., 750 kg/hm2, 1500 kg/hm2, 2250 kg/hm2 and 3000 kg/hm2) on the yield, Cd and Pb contents of vegetable, soil acidity and available heavy metal Cd and Pb contents in soil. Results showed that: Compared with the treatment without using soil conditioner, the application of different dosage of Tebeca soil conditioning could increase vegetable yield by 9.2%∼43.8%, decrease Cd content by 13.3%∼68.0%, Pb content by 12.4%∼71.1%, increase soil pH by 2.7%∼17.6%, decrease exchangeable hydrogen by 7.4%∼42.2%, exchangeable aluminium by 20.5%∼55.4%, respectively. Meanwhile, the content of available Cd and Pb in soil were reduced by 15.6%∼66.1% and 3.6%∼34.7% respectively. Among them, the application effect of Tebeca soil conditioning agent in vegetable production was better when it was applied from 2250 kg/hm2 to 3000 kg/hm2.
Green plantations as biological protection of the atmospheric environment from the negative impact of the highway
Authors: Kharytonova Nataliia , Vyrozhemskyi Valerii , Bezuglyi Artem , Voloshyna Olha
Published: October 2019

Nowadays, the most widespread and significant source of air pollutants is highways and road vehicles. The number of road vehicles in the world has already exceeded 1 billion units and continues to grow steadily. Unsatisfactory road conditions promote increased emissions of harmful substances into the atmosphere which has unfavourable impact on the environment. There are several ways to reduce the negative impact of pollutants from road vehicles on atmospheric environment, including planting the roadside area. Eighty-five cross-sections of the highways in different climatic zones of Ukraine were selected for measurements of the concentration of pollutants in the air in the right of way (ROW) depending on the composition of the traffic flow, traffic volume, geometric parameters of the road and the presence of green plantations were performed. The results show that NO2 and dust increased in all sites. The green plantations can effectively reduce the concentration of harmful emission up to 70%, dependent on plant species and green plantation width.
Overview of urban planning policy and urban green space system at a national level in China
Authors: Xie Junfang , Woolley Helen , Liu Binyi , Elsadek Mohamed
Published: October 2019

The present review aims at understanding urban policy frameworks and context on China’s urban green space system at national level. In order to allow critical reflection on the strengths and weaknesses of urban planning policy and green space system. The rationale of this review is to enhance the overall quality of urban environments and to promote urban sustainability, health and improved living. There is a general convergence of policy trajectories indicating that policymakers, planners and professionals have recognized the mutual interdependence of the relationship between green space and the quality and quantity of housing provision. Overall, improvements have been made to better integrate with urban green space and long-term urban management as a whole to create quality living environments. However, both national policy and regulations lack specification on the quality and quantity of green space and are yet standardized, there is not yet useful guidance or criteria on best practice for design for green spaces, and little reference to green space governance or leadership, management norms and abilities.
Evaluation of treatment efficiency of coal mine drainage and impact on surrounding waters for selected coal mines
Authors: Shan Yao
Published: October 2019

Coal mine water usually has high content of trace elements, leading to contamination of surrounding water bodies. Water treatment technologies are used to remove organic and inorganic matters from coal mine water. To evaluate the treating efficiency of conventional and advanced treatment on coal mine drainage, samples of coal mine, carbonate, surface water, and treated water from the treatment processes were collected and analysed. It turns out that the conventional treatment processes can hardly remove both major ions and trace elements in coal mine water. Reverse osmosis technology can reject major ions effectively, but weak in trace elements removal. The analysis of surface water quality suggested contamination by coal mine water in the coal-mine district. To control the contamination and reuse the coal mine water effectively and safe, it is necessary to evaluate more carefully the efficiency of water treatment and potential environment impact of coal mine water on the surrounding surface and ground waters.
Effects of artificial grassland type on soil water content of degraded land restored by ecological measures in suburban Beijing
Authors: Pang Zhuo , Sun Tiejun , Kan Haiming , Wu Juying
Published: October 2019

Establishment of artificial grasslands is an effective and economic measurement for restoring degraded land, however, established grasslands consume soil water and disturb local water balance as well. To quantify the influence of artificial grasslands on soil water content, we monitored soil volumetric water content (VWC) at depths of 5 cm, 10 cm, 15 cm, 20 cm and 25 cm in artificial grasslands of Bromus inermis Leyss and Medicago sativa continuously throughout 2018. For Bromus inermis Leyss grassland, VWC peaked at depth of 20 cm (0.190±0.053 m3·m−3) and varied little among the rest depths, while for Medicago sativa grassland, VWC increased with depth and the highest value was 0.153±0.047 m3·m−3 at depth of 25 cm. Moreover, VWC in Bromus inermis Leyss grassland was obviously higher than that in Medicago sativa grassland for the whole year at depths of 5 cm, 15 cm and 20 cm, and slightly higher for part of the year at depth of 10 cm, but insignificantly lower at depth of 25 cm. As for water conservation, Bromus inermis Leyss grassland could perform better than Medicago sativa grassland. Under the identical climatic and edaphic conditions, the dramatic differences in VWC between grasslands of Bromus inermis Leyss and Medicago sativa imply that ecohydrological response should be taken into consideration, when selecting measures for ecological restoration.
Assessment of wastewater on-line monitoring system in an important industrial park in Tianjin, China
Authors: Liu Guangxun , Zhi Yanli , Xu Weinan , Yu Yang
Published: October 2019

Chemical oxygen demand and ammonia nitrogen were key water pollutants under state control, and key factories were required to conduct online monitoring. In order to evaluate the accuracy of the online instrument, the online equipment comparison monitoring of 20 key factories in 8 industries was conducted for 4 years. The wastewater of factories in the same industry has similar contaminant discharge concentration. The mean value of relative error absolute value was below 20% for medium and high concentration of chemical oxygen demand (above 30 mg/L) and ammonia nitrogen (above 1 mg/L) in water samples. For high chlorine concentration and coloured water samples, the online monitoring error was large, so the method needs to be improved.
Preparation of activated carbons from a kind of Chinese herbal medicine wastes by phosphoric acid and CO2 activation
Authors: Nie Gang , Hu Yeli , Mi Tie , Liu Yanxiang , Xin Shanzhi
Published: October 2019

The effects of parameters on the adsorption capacity of activated carbons (AC) prepared from Chinese Herbal Medicines Wastes (CHMWs) by phosphoric acid and CO2 activation were studied. Response surface methodology (RSM) was used to optimize the process parameters for preparing activated carbon from CHMWs. The results showed that the optimal conditions were as follows: impregnation ratio of 2.61, activation temperature of 700 °C, activation time of 2.5 h and the CO2 flow rate was 50mL/min. The adsorption value of iodine and methylene blue of the resultant activated carbon was 626.83 mg/g, 278.99 mg/g, respectively. The Activated Carbon prepared from Chinese Herbal Medicines Wastes (CHMWs) shows high adsorption capacity and well-developed pore structure.
Fracture-cave carbonate reservoir permeability modelling based on conventional log and well deliverability predication: A case study of the Amu Darya Gas field in Turkmenistan
Authors: Li Ming , Zhang Ming , Liu Lingli , Guo Tongcui , Lv Jietang , Zhang Liangjie , Chen Pengyu , Guo Chunqiu , Wang Hongjun
Published: October 2019

The carbonate fracture-cave reservoir is developing in carbonate gentle slope reef flat in east Amu Darya Gas field. Due to the serious heterogeneity of fracture-cave reservoirs, it is difficult to evaluate the productivity of different wells and different reservoir sections. Based on conventional log, core, image log and magnetic resonance log. The sensitive parameters contributed to reservoir permeability are studied, and the conventional log, magnetic log and image log of key well are set up to march core permeability and propagate other fracture-cave carbonate wells. Finally based on log porosity and permeability model result, the well deliverability is evaluated and the well deliverability evaluation results are match with the DST results. The Amu Darya Gas field carbonate fracture-cave permeability model and deliverability evaluation flowcharts and methods were build up and can give instructions for other fracture-cave carbonate reservoir.
Prototype geological model of distributary channel based on the high density well pattern
Authors: Wang Zhiqiang , Li Rubin , Song Baoquan , He Yuhang
Published: October 2019

The western part of the central zone lies in the middle of the Saertu anticline structure. It can be divided into 77 sedimentary units, with the permeability ranging from less than 10 mD to more than 1000 mD. Diversity of plane sand body morphology, phase change frequently. Based on the high density logging data in the west of the central district, the prototype geological model of distributary channel sand body is studied, and 6 sedimentary models of distributary channel in 3 sedimentary environments are established. The Upper plain was mainly developed: composite type. The lower plain is mainly developed: the split-band type and the interwoven network type; the delta front is furcated dendritic, single continuous and discontinuous type. Geometric parameters of different distributary channels are obviously affected by the sedimentary environment, and the scale, curvature and width-thickness ratio of distributary channels along the sedimentary direction all decrease from large to small.
Parametric electromagnetic transfer function estimation at USArray Site MNF34
Authors: Xu Xinyi , Butala Mark D.
Published: October 2019

We propose a new parametric approach to electromagnetic transfer function (EMTF) estimation which has attributes not found in the nonparametric approach most extensively used by the magentotelluric (MT) community. Firstly, parametric EMTFs are smooth by construction, which is consistent with the underlying physics. Secondly, fewer parameters are generally required to represent an EMTF by parametric means. Thirdly, our parametric approach can simplify data quality control and editing of time series because of the direct operation in the time domain. Our approach is based on the mature discipline of system identification which is concerned with parametric transfer function determination given system input and output. In this study, MT data from one USArray site are analyzed, showing a statistical advantage in reproducing measured geoelectric field time series using a parametric model EMTF versus the standard EMTF approach.
Numerical Simulations for the Tip-Jet Drive Rotor Based Upon Momentum-Source Method
Authors: Fei CUI , Zhuang Jian , Wang Bo
Published: October 2019

Based upon a momentum-source method, a numerical simulation method has been developed to calculate the tip-jet drive rotor/fuselage flowfield. The momentum-source term is used to describe the effect of rotor on its flowfield. The mass-source term is used to describe the tip-jet. According to the characteristics of rotor/fuselage flowfield and requirements of momentum-source and mass-source method, a hybrid mesh generation approach is developed. In the present method, on the basis of the known movement, geometric and aerodynamic characteristics on blade section, a scheme containing momentum-source and mass-source term is adopted for the solution of N-S equations. By the present method, the downwash flowfields of rotor and rotor/fuselage are simulated, and some meaningful conclusions are obtained.
Application of Arbitrary Vortex Method in Wind Tunnel Axial Fan Design
Authors: Dachuan Xu , Haifeng Wang , Xiaoli Qu , Yongsheng Yu , Yu Shi , Fang Zhao
Published: October 2019

The flow axial velocity is assumed equal everywhere in free vortex design method, and the pressure rise of flow pass through fan is assumed also equal at different radial height. But in arbitrary vortex design method, on the assumption that axial velocity along radial is variable, the flow rotational velocity along radial is not must an inverse distribution. Therefore, arbitrary vortex design method could have a more uniform axial velocity at the outlet of fan system by regulating the rotational velocity distribution. In the numerical simulation, the fan of a pilot wind tunnel is used as physical model. By comparison with the experimental data the reliability of the numerical simulation could be verified. Two fan physical models are established which are based on the designs of arbitrary vortex method and free vortex method. The result of numerical simulation indicated that compared to the free vortex method, the arbitrary vortex fan minished the separation on the tip and root of blade, obtained a more well uniform axial velocity distribution at the outlet of fan system. And the efficiency of blade is also increased by arbitrary vortex method.
Comparative Analysis of the Flow Field in the Lower Bend at Different Rotation Angles
Authors: Liu Zhaoliang , Wang Jinlong , Yuan Chengdong
Published: October 2019

In order to obtain the influence of the distribution of the flow field in the lower bend at different rotation angles on the fluid flow, Fluent software was used to conduct numerical simulation of the flow field in the bend at different rotation angles, and the influence rule of the shape difference of the secondary flow in the lower bend at different rotation angles was simulated. The simulation results show that the 90 °rotation Angle bend, its internal gas phase flow field better than other simulation Angle, secondary flow phenomena delay happened, reduce reflux area, syphon is helpful to improve the flow state; With the change of the rotation Angle, the tangential velocity of the outlet section of the bend increases continuously, which is conducive to the smooth gas-solid phase separation, but the pressure drop of the system also increases, resulting in the energy loss of the system. As a result, the Angle of 90 ° canary after rotation Angle for the simulation of the optimal point of view, for later engineering application provides data to support and help.
Study on Large-scale Dynamic Measurement of Lunar Rover with iGPS
Authors: Chen Qiwei , Tang Laiying , Yang Zaihua , Wang Linzheng , Feng Wei , Zheng Shengyu , Yi Wangmin
Published: October 2019

In the motion simulation test, the real-time position and orientation of lunar rover need to be measured accurately in a wide area to test lunar rover’s motion performance on simulated lunar soil. The iGPS system, whose accuracy is better than 1mm and sampling frequency is higher than 10 Hz, is applied to measure the position and orientation of lunar rover in the test. Large-scale dynamic measurement of lunar rover with iGPS is studied in this paper. This paper mainly discusses the layout methods of laser transmitters and receiving sensors, and analyzes the position and orientation measurement accuracy of different layout methods to achieve optimization layout. It can provide some reference for the research of large-scale dynamic measurement of other rigid objects.
Analysis on Synchronizing and Gear Shifting Force of Commercial Vehicle Powertrain
Authors: Yan Zhengfeng , Zhao Peisheng , Wu Yajun
Published: October 2019

Based on a commercial vehicle transmission as the research object, the paper analyses the influence for commercial vehicle powertrain synchronization and shift performance by the rotational inertia of the clutch driven plate assembly and transmission input speed. According to the synchronization and shifting mechanism of the transmission, transmission shift dynamics model was established. Analyzing the causes of shift impact and the critical shifting force for mis-engagement put forward the shift control strategy to avoid shift impact. We can draw a conclusion that optimizing the clutch driven plate inertia parameter during clutch design can effectively improve the shift performance of the transmission.
High-Speed Performance of a Tamping Machine with Closed-Type Hydrostatic Propulsion Drive
Authors: Zhou Zirong , Cai Xiong , Wang Wenlin
Published: October 2019

It is significant to understand and optimize the parameters of the hydraulic system to pursue both better low-speed operation and high-speed mobility performance of a tamping machine. A mathematical model formulating the high-speed performance of a tamping machine with a closed-type hydrostatic propulsion drive system is established in this study, a simulation model is built in the AMEsim software environment based on the mathematical model. Simulation results show that the tamping machine with a closed-type hydrostatic propulsion drive system has got a 35-100 km/h scope for high-speed mobility, and the acceleration performance is also satisfactory. The mathematical model established and results obtained in this work will be instructive for further parameter sensitivity analysis and tamping machine design optimizations.
Joint Trajectory Time Optimization of Cobot Based on Particle Swarm Optimization
Authors: Zhenyi Cheng
Published: October 2019

In order to improve the working efficiency of the robot and make the welding quality of the part of skin group improved greatly. We Researched on the end trajectory of the Cobot. In the application scenario of Friction Stir Welding (FSW) test bench, an algorithm of joint space trajectory is proposed according to the kinematics characteristics of the robot and the practical application needs.Based on particle swarm optimization (PSO), the motion trajectory of robot joint is fitted by high order polynomial interpolation. While ensuring the end trajectory, the stability of the joint motion is guaranteed. The simulation experiment is carried out by using MATLAB software. The joint space optimal motion planning is realized. The comparison algorithm is verified by experiments. According to the experimental results, the particle swarm optimization algorithm improves the efficiency of the cooperative robot significantly. It is helpful to the end stability of friction stir welding robot.
Study on Cure Deformation of Metal/CFRP Laminated Composites
Authors: Liu Xueshu , Li Jinlei , Lei Jianhua , Wang Qi , Gao Qian
Published: October 2019

During the curing process of composite materials, the differences of the heat transfer ability and mechanical properties of material in various directions result in residual stresses and curing deformation in the composite after curing. Curing deformation has adverse effect on the mechanical performance of composites. The development of internal stress during curing may cause matrix cracking, delamination, warpage and rebound deformation of composites. In this paper, numerical simulation is used to predict the curing deformation of components, thereby reducing production costs and improving production efficiency as well. According to the curing kinetic equation, the HETVAL subroutine was firstly developed to calculate the temperature field and the curing degree field of the curing process. UMAT and UEXPAN subroutines were then applied to solve the mechanical constants and thermal strain and curing shrinkage strain during the curing process. After the proposed model was verified, the deformation of the metal composite co-cured components was studied. It was found that when the thickness ratio of metal to CFRP is one to one the composite gains the greatest geometrical deviation after curing.
Performance Analysis of Drilling Test of Aramid Fiber Composite
Authors: lei Jin , jing Qi
Published: October 2019

Aramid fiber-reinforced polymer (AFRP) is a typical difficult material to machine. It is easy to occur defects such as ablation and burr in the drilling process due to the serious non-uniformity and heterotrophy of these material properties, as well as low heat transfer coefficient and high fibre toughness of the aramid fibre, which remarkable affects the machining quality and assembly accuracy. In this paper, three types of drills with different cutting edge shapes were compared to analyse the influence of drilling on cutting force, cutting temperature and machining quality. The results showed that the tool geometry has a great influence on the drilling performance of AFRP. Due to poor drilling quality, 8-face drill and twist drill are not suitable for drilling AFRP drilling tools. The machining quality of Brad & Spur drill is relatively good, which can meet the drilling requirements of AFRP.
Technological Rule of Ultrasonic Assisted Magnetic Abrasive Finishing of Titanium Alloy
Authors: Jiang T Y , Ma F J , Liu X , Liu Y , Zhang S F , Sha Z H
Published: October 2019

The influence of machining time, ultrasonic amplitude, spindle speed and machining gap on surface roughness and material removal rate were studied and analysed through the experiment of UAMAF of titanium alloy. The results show that the surface roughness decreases rapidly in the beginning and then gradually stabilizes as the machining time increases. The surface roughness reduces from the original Ra0.94μm to Ra0.10μm, when the machining time reaches 30min that is optimum machining time. The material removal rate drops approximately linearly with the increase of machining time. The surface roughness decreases significantly and the material removal rate increases rapidly as the ultrasonic amplitude rises. The surface roughness reduces to Ra0.12μm and the material removal rate increases to 30.5mg/h, when the ultrasonic amplitude is up to 14μm. The surface roughness decreases in the beginning and then increases, and the material removal rate rises in the beginning and then falls, as the spindle speed increases. The surface roughness achieves a minimum of Ra0.11μm and the material removal rate reaches a maximum of 22.74mg/h, when the spindle speed is 1400r/min. The surface roughness drops in the beginning and then rises, and the material removal rate increases in the beginning and then decreases, as the machining gap enlarges. The optimum machining gap is about 1.25mm. In this case, the surface roughness achieves a minimum of Ra0.16μm, and the material removal rate reaches a maximum of 17.7mg/h.
Study on the Interaction between Vibration Mode and Radiated Sound of Conical Shell
Authors: Jiang-Hai Wu , Fang An , Yong Duan , Yu-Dong Sun
Published: October 2019

Conical shell is one of the most common structures in engineering, especially in airplane and ship structures. In order to reduce its vibration and radiation sound, which were widely concerned, this paper used BEM method to analysis the vibration characteristic,radiated sound and the interaction between them. Three different models were established to study the difference between conical shell in the air and under water. The numerical results demonstrate that the existence of water has great influences on the frequency and amplitudes of the radiated sound power. Due to the low density, the natural frequency of conical shell dominants the peak frequency of radiation sound in the air. And the contribution of each vibration mode to the radiation sound different from each other. The results of this study can provide some valuable suggestions for the position selection of active control actuators on conical shell.
Development of Explosion-containment Vessel with 3 kg TNT Equivalent
Authors: Zhou Kan , Huang Ge , Fang Kai , Huang Huang , Bai Haijun
Published: October 2019

In this paper, the design theory of explosion-containment vessel is studied, the charge ratio distance, incident overpressure and reflection overpressure acting on the inner wall of the explosion-containment vessel are calculated when 3kg TNT is exploded in it, the transient load generated in the explosion is converted into equivalent static load by the method of dynamic coefficient, and the main wall thickness of 3kg TNT equivalent explosion-containment vessel is determined. A 3kg TNT equivalent capsule explosion-containment vessel is designed and tested the explosion performance, the explosion performance test results show that the design of the 3kg TNT equivalent explosion-containment vessel is reasonable, safe and reliable, and it is of great practical significance to apply it to the transportation and destruction of weapons and ammunition and emergency treatment.
Parametric Analysis of Wave-shaped Metal Sealing Ring Based on Hierarchical Solution Method
Authors: miaotian Zhang , shuangfu Suo , yu Feng , jianwen Shi , guoying Meng
Published: October 2019

The wave-shaped metal sealing ring is widely used in the aerospace field, whose failure will directly affect the flight safety and even cause major personal accidents and economic losses. The performance optimization problem of the wave-shaped seal is a multi-objective optimization problem, and the multiple targets are affected by the geometric design factors, and are not completely independent of each other. In this paper, for the sealing problem under the severe conditions of aero-engine, the corrugated metal sealing ring is taken as the research object. The W-shaped metal sealing ring is selected as an example, and the finite element model is established by using ANSYS software. Sealing, stability and resilience are chosen as indicators to evaluate the sealing performance. The multi-objective optimization problem is transformed into a single-objective optimization problem by hierarchical solution method, and the sealing structure is parameterized. The optimization results of the geometric parameters of the sealing ring are highly consistent with the product manual of the sealing ring. The correctness and feasibility of the optimization design method based on the analysis of three aspects of performance and the hierarchical solution for dimension reduction are verified.
The Dynamic Performance Study of Six-Dimensional Dynamic Force Generator
Authors: Hongfei Cui , Quan Chen , Wei Li , Limeng Tan , Mingyan Jiang , Deqiang Song , Zheng Li
Published: October 2019

A six-dimensional dynamic force generating device is developed based on the dynamic performance calibration requirement of a six-dimensional force test platform based on the exciter force generating unit. The finite element software is used to perform modal analysis on the dynamic force generating device to obtain the natural frequency response of the device. Based on the finite element analysis results, the second-order transfer function at the sixth-order natural frequency point of the device is obtained, and the amplitude-phase frequency characteristic curve is obtained. Combined with the characteristic parameters of the exciter, the relationship curve between the excitation frequency and the excitation force under the influence of the natural frequency of the device is obtained. The comprehensive of finite element method and calculation results show that the designed dynamic force generating device can meet the requirements of use. According to the analysis results, it is found that the excitation capability can be maintained at a low frequency state to achieve high amplitude fixed frequency excitation, and low amplitude fixed frequency excitation is realized at a high frequency state.
A Test Scheme Design for High Speed Active Cabin Separation
Authors: Feng Wei , Li Changxun , Meng Fanwei , Chen Qiwei , Yi Wangmin , Zheng Shengyu , Wang Linzheng , Wang Chenxing , Zhang Lili
Published: October 2019

In Mars explorations, the EDL (Entry, Descent and Landing) process is autonomously controlled, called “black 7minutes”. In order to verify the EDL process of the Mars probe cabin (the heatshield facing the Mars surface and the aeroshell back to the surface of Mars) high speed separated, this paper proposes an active motor pull separation scheme and controlling method of axial force, normal force and torque multi-coupling, solves the technological problem of the force applied, followed and safe recycling cabin in short time and distance, establishes a test system and completed the separation test of the heatshield and the aeroshell by real product. The results show that the test success criteria are met and the test scheme is successful. This method and experimental system can be used not only in the separation experiment of Mars probe, but also in the separation or servo simulation of other detectors or general mechanisms, can be widely used or used for reference. This paper explains the general scheme and key technology, followed by other papers on ADAMS Simulation, influence on air-resistance and so on.
Test Research on Airdrop Shock Vibration of Armored Vehicles
Authors: Hou Jun-fang , Yu Guang-chun , Zhang Wei-hua , Wang He-ping , Liang Yuan-yuan
Published: October 2019

In view of the airdrop adaptability of a lightweight high-mobility wheeled armored vehicle, the shock vibration of the vehicle’s onboard electronic equipment under simulated airdrop was tested and the shock characteristic of the equipment was analyzed. The test results show that the onboard equipment of the airdrop vehicle is mainly subjected to three stages of shock vibration, which includes the crash of the lifting rope, shock of the cushion airbag and the rebound shock. The cushion airbags can effectively reduce the shock acceleration peak of the onboard electronic equipment of the light wheeled armored vehicle, and the shock peak of the onboard computer and power supply is about 9-10 g with the shock duration of 0.15-0.2 s. While compared with the shock of the base, the buffering effect of the isolators to the airdrop shock vibration is not satisfied. Resonances of the isolation system are caused by the airdrop shock and the shock peaks of the tested electronic equipment are higher than that of the base.
Research on the Effectiveness of Service Design Based on the Quantitative Method of Kansei Engineering—Taking the LANNA Coffee Service Process as an Example
Authors: Wang Zhengyu , Zhou Meiyu , Liu Xiangyu
Published: October 2019

The increasing enrichment of industrial products has made it difficult to meet the growing consumer demand for the material functions of products. This has caused the non-material or mental function of the product to be strengthened, promoted product design to gradually expand from the material dimension to the non-material service design, and accelerated the transformation of the manufacturing industry into a service-oriented product manufacturing. Service design has gradually become a new hot academic research field in product design. As a traditional industry, how to promote the transformation of coffee shop from “product” to “service” has become the research direction of this study. After investigation, we find some problems in coffee shop service, such as single focus, unbalanced proportion distribution of internal structure of service design, as well as vague and uncertain user demand. This paper attempts to use the forward quantitative inference method of Kansei Engineering to analyze consumers’ perceptual demands for coffee shop services through questionnaires, the overall process of service and the weight of service elements. We also try to set up the service elements and multivariate linear regression equation between the service effectiveness, put forward the service design effectiveness evaluation method, and on this basis, provide the analysis of the service system to serve the interests of the parties with complimentary method to make the adjustment and evaluation of service design more intuitive.
Pulling back singularities of codimension one objects
Authors: Giraldo Luis , Roeder Roland
Published: October 2019

We prove that the preimage of a germ of a singular analytic hypersurface under a germ of a finite holomorphic map

g
:
(

C

n

,

0

)
→
(

C

n

,

0

)

g: (\mathbb {C}^n,\mathbf {0}) \rightarrow (\mathbb {C}^n, \mathbf {0})

is again singular. This provides a generalization of previous results of this nature by Ebenfelt-Rothschild [Comm. Anal. Geom. 15 (2007), no. 2, 491-507], Lebl [ArXiv preprint https://arxiv.orglabs/0812-2498], and Denkowski [Manuscripta Math. 149 (2016), no. 1–2, 83–91]. The same statement is proved for pullbacks of singular codimension one holomorphic foliations.
Reference values for handgrip strength: data from the TCLSIH cohort study
Authors: Wu Hongmei , Liu Mingyue , Zhang Qing , Liu Li , Meng Ge , Bao Xue , Gu Yeqing , Zhang Shunming , Sun Shaomei , Wang Xing , Zhou Ming , Jia Qiyu , Song Kun , Niu Kaijun
Published: October 2019

Background

although handgrip strength (HGS) is considered an excellent predictor of morbidity and mortality, there are few reference data available, especially across life from young to old populations.

Objective

to investigate the reference values and determinants for HGS in a large Chinese adult population.

Design

this cross-sectional study used data from the Tianjin Chronic Low-Grade Systemic Inflammation and Health Cohort Study ranging from 2013 to 2017.

Setting and subjects

in total, 37,707 Chinese adults aged 18–93 years with measures of HGS were included.

Methods

HGS was measured using a handheld digital dynamometer. The percentile distribution of HGS, as well as mean (standard deviation) values of HGS, was calculated according to sex and age categories. The Pearson’s or Spearman’s correlation coefficient and multiple linear regression were also used.

Results

the peak mean value of HGS was 45.2 ± 6.88 kg in men and 26.8 ± 4.65 kg in women. Different reference values for each sex and age category are present. The prevalence of low HGS was 7.69% in men and 6.46% in women. Multiple regression analysis showed that almost 72.5% of HGS variability can be explained by sex, age, height and weight.

Conclusions

the HGS reached peak at 40 years old, maintained or slightly lowered between ages 40 and50 and then start an accelerated decline after 50 years old. Reference values of HGS should be stratified by sex and age group. HGS variability can be largely explained by sex, age, height and weight.