High Efficient Methods of Content-based 3D Model Retrieval

Content-based 3D model retrieval is of great help to facilitate the reuse of existing designs and to inspire designers during conceptual design. However, there is still a gap to apply it in industry due to the low time efficiency. This paper presents two new methods with high efficiency to build a Content-based 3D model retrieval system. First, an improvement is made on the ＂Shape Distribution （D2）＂ algorithm, and a new algorithm named ＂Quick D2＂ is proposed. Four sample 3D mechanical models are used in an experiment to compare the time cost of the two algorithms. The result indicates that the time cost of Quick D2 is much lower than that of D2, while the descriptors extracted by the two algorithms are almost the same. Second, an expandable 3D model repository index method with high performance, namely, RBK index, is presented. On the basis of RBK index, the search space is pruned effectively during the search process, leading to a speed up of the whole system. The factors that influence the values of the key parameters of RBK index are discussed and an experimental method to find the optimal values of the key parameters is given. Finally, ＂3D Searcher＂, a content-based 3D model retrieval system is developed. By using the methods proposed, the time cost for the system to respond one query online is reduced by 75% on average. The system has been implemented in a manufacturing enterprise, and practical query examples during a case of the automobile rear axle design are also shown. The research method presented shows a new research perspective and can effectively improve the content-based 3D model retrieval efficiency.

High Yield and Efficient Cultivation Techniques of Rice under Rice- fish Intergrowth Model in Chengdu

The integrated planting and breeding of paddy fields is a kind of eco-planting and breeding mode which makes rice and aquatic animals benefit from each other,greatly reducing the harm of rice pests and diseases,using less or even no fertilizers or pesticides,greatly reducing the agricultural non-point source pollution,thus achieving the " multiple use of water,multiple harvests in one field,grain and fishing winwin,ecological and high efficient use. " In this paper,the high yield and efficient cultivation techniques of rice under the rice-fish intergrowth model in Chengdu was introduced from the aspects of selecting good paddy fields for fishing,using appropriate rice varieties,soaking disinfection,timely sowing and nurturing strong seedlings,reasonable close planting,reasonable fertilization,scientific water management,scientific pest control and rice harvests.

Low organic matter abundance and highly efficient hydrocarbon generation of saline source rock in the Qaidam Basin,NW China

The geochemical analysis and experimental simulation are comprehensively used to systematically study the hydrocarbon generation material,organic matter enrichment and hydrocarbon generation model of Paleogene source rock in the Western Qaidam Depression,Qaidam Basin,NW China.Three main factors result in low TOC values of saline lacustrine source rock of the Qaidam Basin:relatively poor nutrient supply inhibits the algal bloom,too fast deposition rate causes the dilution of organic matter,and high organic matter conversion efficiency causes the low residual organic carbon.For this type of hydrogen-rich organic matter,due to the reduction of organic carbon during hydrocarbon generation,TOC needs to be restored based on maturity before evaluating organic matter abundance.The hydrocarbon generation of saline lacustrine source rocks of the Qaidam Basin is from two parts:soluble organic matter and insoluble organic matter.The soluble organic matter is inherited from organisms and preserved in saline lacustrine basins.It generates hydrocarbons during low-maturity stage,and the formed hydrocarbons are rich in complex compounds such as NOS,and undergo secondary cracking to form light components in the later stage;the hydrocarbon generation model of insoluble organic matter conforms to the traditional“Tissot”model,with an oil generation peak corresponding to Ro of 1.0%.

Numerical modeling of wave equation by a truncated high-order finite-difference method

Finite-difference methods with high-order accuracy have been utilized to improve the precision of numerical solution for partial differential equations. However, the computation cost generally increases linearly with increased order of accuracy. Upon examination of the finite-difference formulas for the first-order and second-order derivatives, and the staggered finite-difference formulas for the first-order derivative, we examine the variation of finite-difference coefficients with accuracy order and note that there exist some very small coefficients. With the order increasing, the number of these small coefficients increases, however, the values decrease sharply. An error analysis demonstrates that omitting these small coefficients not only maintain approximately the same level of accuracy of finite difference but also reduce computational cost significantly. Moreover, it is easier to truncate for the high-order finite-difference formulas than for the pseudospectral for- mulas. Thus this study proposes a truncated high-order finite-difference method, and then demonstrates the efficiency and applicability of the method with some numerical examples.

INVESTIGATION OF SURFACE TEMPERATURE IN HIGH-EFFICIENCY DEEP GRINDING

A new thermal model with triangular heat flux distribution is given in high-efficiency deep grinding. The mathematical expressions are driven to calculate the surface temperature. The transient behavior of the maximum temperature on contact area is investigated in different grinding conditions with a J-type thermocouple. The maximum contact temperatures measured in different conditions are found to be between 1 000 ℃ and 1 500 ℃ in burn-out conditions. The experiment results show good agreement with the new thermal model.

Efficiency of Model Induction Motor Using Various Non-Oriented Electrical Steels

The performance of a 3-phase 6-pole 400 W inverter-drive induction motor was investigated using a variety of non-oriented electrical steels for stator core at PWM inverter fundamental wave frequencies of 30 to 300 Hz. There existed an optimum Si content of the material depending on the tooth flux density. Both reduction of material thickness and stress-relief annealing of the stator core improved the motor efficiency. The influence of Si content on the efficiency was small at lower PWM frequencies, while at higher frequencies the motor efficiency increased with increasing Si content. The Cu loss WC increased and the Fe loss Wi counteractiveiy decreasedwith increasing Si content at lower frequencies; while at higher frequencies Wi had dominant effect on the efficiency. Newly developed materials RMA, having lower Fe losses after stress-relief annealing and higher flux densities with lower Si contents, showed motor efficiencies superior to conventional J1S grade materials with comparable Fe losses.

The Application of the Trial-Discovery Model to English Grammar Teaching in Senior High Schools

In senior high schools, great importance and attention are required to be attached to grammar teaching and learning. However, a majority of teachers either apply the traditional method or neglect grammar teaching and learning, both of which go against the ideas of the new curriculum of the high school. To solve the problem, based on the constructionist theory, Halliday＇s theory of register, and the trial-discovery model, the trial-discovery English grammar teaching model was constructed. To find out whether this teaching model is more effective than the traditional grammar teaching, an experimental study of the trial-discovery model in senior English grammar teaching is carried out. This study deals with the problem how we can improve the efficiency of grammar teaching, that is by increasing the students＇ learning interest and improving the accuracy in English writing. After the analysis of qualitative and quantitative data collected through questionnaires, interviews, and writing tests, the study reveals that the trial-discovery grammar teaching is more effective to stimulate the students＇ interest in learning grammar, and is more helpful to improve the accuracy and complexity in English writing than the traditional grammar teaching

三新并举推动高质量发展的全要素效率测度及时空演化特征

新质生产力、新型工业化和新型城镇化的三新并举作为中国式现代化进程中的又一伟大创举,是实现高质量发展的必由之路。本文将三新并举视作投入要素、高质量发展作为产出成果,采用SBM模型测度三新并举全要素效率,并运用类方差分解、Moran指数和收敛模型等方法考察其时空演化特征。研究发现:2006~2022年三新并举对高质量发展的推动效果愈发明显,其中,新质生产力是推动高质量发展的中坚力量;三新并举全要素效率的空间差异呈现发散趋势,四大板块的区域间差异是总体差异的主要来源,空间集聚效应促使新质生产力和新型工业化的全要素效率呈现收敛态势;三新子要素全要素效率的集聚重心偏向东部地区,新质生产力和新型城镇化的全要素效率分别表现为南强北弱和北强南弱,新型工业化全要素效率历经南强北弱到北强南弱的转变。

Data Processing Model of Coalmine Gas Early-Warning System

The data processing mode is vital to the performance of an entire coalmine gas early-warning system, especially in real-time performance. Our objective was to present the structural features of coalmine gas data, so that the data could be processed at different priority levels in C language. Two different data processing models, one with priority and the other without priority, were built based on queuing theory. Their theoretical formulas were determined via a M/M/I model in order to calculate average occupation time of each measuring point in an early-warning program. We validated the model with the gas early-warning system of the Huaibei Coalmine Group Corp. The results indicate that the average occupation time for gas data processing by using the queuing system model with priority is nearly 1/30 of that of the model without priority.

Constitutive modeling of ultra?fine?grained titanium flow stress for machining temperature prediction

This work investigates the machining temperatures of ultra-fine-grained titanium(UFG Ti),prepared by equal channel angular extrusion,through analytical modeling.UFG Ti has great usefulness in biomedical applications because of its high mechanical strength,sufficient manufacturability,and high biocompatibility.The temperatures were predicted using a physics-based predictive model based on material constitutive relation and mechanics of the orthogonal cutting process.The minimization between the stress calculated using Johnson–Cook constitutive model and the same stress calculated using mechanics model yields the estimation of machining temperatures at two deformation zones.Good agreements are observed upon validation to the values reported in the literature.The machinability of UFG Ti is investigated by comparing its machining temperature to that of Ti–6Al–4V alloy under the same cutting conditions.Significantly lower temperatures are observed in machining UFG Ti.The computational efficiency of the presented model is investigated by comparing its average computational time(~0.5 s)to that of a widely used modified chip formation model(8900 s)with comparable prediction accuracy.This work extends the applicability of the presented temperature model to a broader class of materials,specifically ultra-fine-grained metals.The high computational efficiency allows the in situ temperature prediction and optimization of temperature condition with process parameters planning.

A Perceptual Video Coding Based on JND Model

In view of the fact that the current high efficiency video coding standard does not consider the characteristics of human vision, this paper proposes a perceptual video coding algorithm based on the just noticeable distortion model (JND). The adjusted JND model is combined into the transformation quantization process in high efficiency video coding (HEVC) to remove more visual redundancy and maintain compatibility. First of all, we design the JND model based on pixel domain and transform domain respectively, and the pixel domain model can give the JND threshold more intuitively on the pixel. The transform domain model introduces the contrast sensitive function into the model, making the threshold estimation more precise. Secondly, the proposed JND model is embedded in the HEVC video coding framework. For the transformation skip mode (TSM) in HEVC, we adopt the existing pixel domain called nonlinear additively model (NAMM). For the non-transformation skip mode (non-TSM) in HEVC, we use transform domain JND model to further reduce visual redundancy. The simulation results show that in the case of the same visual subjective quality, the algorithm can save more bitrates.

金融科技创新如何促进实体经济高质量发展——基于金融服务效率的机制分析与空间计量

金融科技创新对于提升金融服务效率,服务实体经济具有重要意义。基于2011—2021年我国31个省份的平衡面板数据,运用空间计量模型和中介效应检验,研究金融科技创新对实体经济高质量发展的直接影响、间接效应和作用机制。研究发现:金融科技创新不仅能直接促进本地区实体经济高质量发展,而且具有正向空间溢出,对邻近地区实体经济高质量发展呈现渐进、动态的长期影响。中介效应和异质性检验表明,提升金融服务效率是金融科技创新促进实体经济高质量发展的主要机制。在金融科技创新监管试点地区,金融科技对实体经济高质量发展的直接影响、间接效应和中介效应均明显高于非试点地区。因此,要优化金融科技业态空间布局,提升金融服务效率,深化金融科技创新监管试点,以更好地服务实体经济高质量发展。

黄河流域农业碳排放效率与农业高质量发展的互动关系

为推进农业绿色低碳和高质量发展,利用超效率SBM模型和熵值法,测算了黄河流域农业碳排放效率和农业高质量发展水平,并采用VAR模型探讨了二者的互动关系。结果表明:1)黄河流域农业碳排放效率整体呈上升趋势,甘肃、山西两省,四川、山东、河南、陕西、青海五省,宁夏、内蒙古两自治区分别处于较低、中等、较高水平;2)农业高质量发展水平整体呈波动上升趋势,陕西、山西、宁夏、内蒙古四省(区),青海、甘肃两省,河南、四川、山东三省分别处于较低、中等、较高水平;3)农业碳排放效率提升促进了农业高质量发展,而农业高质量发展对农业碳排放效率影响不显著。基于研究结果,从绿色、可持续发展等方面,提出了提升黄河流域农业碳排放效率和推动农业高质量发展的建议。

高质量发展下区域绿色物流效率评价研究

区域绿色物流是推进物流业绿色发展的重要元素。基于DFSO提出高质量发展视域下绿色物流框架并构建效率测度指标体系,运用改进三阶段DEA模型对中国30个省(市)进行实证研究,分析各因素对绿色物流效率的影响。结果表明高质量发展视域下省域绿色物流整体效率不高,地区差异明显,纯技术效率是制约其发展的主要因素;高质量发展各方面均对绿色物流效率有不同程度的影响,但二者间的协调仍处初级阶段。基于此,提出高质量发展视域下区域绿色物流效率提升的对策建议。研究能够为相关部门衡量高质量发展时期物流业绿色发展成效、精准施策提供参考。

中国高技术产业科技成果转化效率和投入产出结构分析

为进一步探究我国高技术产业中各个行业科技成果转化效率及其投入产出结构,利用2009—2021年的面板数据,采用超效率SBM模型对中国高技术产业科技成果转化效率进行研究,分析中国高技术产业15个行业的科技成果转化综合效率和投入冗余、产出不足,为高技术产业及其行业调整优化投入产出结构、提升科技成果转化效率提供基础。研究发现,中国高技术产业科技成果转化效率呈现出先下降再波动上升的趋势,各行业均呈现波动上升的良好发展趋势,但整体水平不高,行业间差距较大;行业间R&D活动人员、技术改造经费和科技活动经费中的政府资金投入冗余,新产品销售收入产出不足问题突出。基于上述结论提出根据行业特点,先转换再精减冗余人员、重视科研人员再教育、调整资金分配结构、转变政府干预方式、建立健全多渠道合作机制、注重市场需求导向促进理论成果市场化等建议,以进一步提升高技术产业科技成果转化效率。

高质量发展目标下脱贫县农业产业化与农地利用生态效率耦合协调分析:以江西省为例

探究脱贫县农业产业化与农地利用生态效率耦合协调关系,对促进农业高质量发展具有重要意义。基于新发展理念,以江西省25个脱贫县为研究对象,构建农业产业化与农地利用生态效率耦合评价体系,借助耦合协调模型和泰尔指数模型测度两者的耦合协调水平及其区域差异。结果表明:(1)2011—2020年,江西省脱贫县农地利用生态效率总体水平较高,年均值为0.738,赣南地区高于赣中和赣北地区;(2)2011—2020年,江西省脱贫县农业产业化发展指数总体水平较低,年均值为0.414,赣北地区最高,其次为赣中,赣南最低;(3)2011—2020年,脱贫县农业产业化与农地利用生态效率耦合协调指数由期初的0.321升至期末的0.342,总体处于中度失调和轻度失调阶段;(4)脱贫县地区内差异对泰尔指数总体贡献最大,县域农业发展协调性较弱。进一步分析可以发现,市场与政府的作用差异是导致农业产业化水平与农地利用生态效率存在差异的主要原因,综合运用行政和市场手段推动农业产业化发展是提高两者耦合协调水平的关键。

“双碳”目标下黄河流域绿色技术创新效率评价及影响因素

基于“双碳”目标视角,采用超效率动态网络SBM模型测算黄河流域82市(盟)2011—2021年绿色技术创新的综合效率、科技研发效率及成果转化效率,并利用面板Tobit回归模型检验外部环境因素对三种效率的影响。结果表明:将CO_(2)排放量纳入指标体系后,中下游地区绿色技术创新综合效率得以提升,上游地区效率反而下降;黄河流域绿色技术创新综合效率呈波动上升趋势,科技研发效率起引擎作用;黄河流域绿色技术创新综合效率区域差异明显,成果转化效率差异是综合效率差异的主要来源;经济发展水平、产业结构高级化、人力资本禀赋、对外开放水平、政府支持力度和环境规制强度对三种效率的影响具有区域异质性。建议黄河流域提高绿色技术创新能力,完善创新成果转化平台,推动能源和产业结构升级。

我国电动机再制造技术与再制造企业商业模式

电动机作为一种在生产生活中广泛应用的装备,每年在消耗大量能源的同时也产生了大量寿命到期的废弃产品。再制造作为一种将寿命到期的废旧产品利用再制造技术加工成新产品的工程活动,拥有低能耗、低成本、低污染的特点,为废旧电动机的处理带来了新的途径。面对再制造产业带来的新的价值获取方式和新的市场环境,再制造企业通过改变商业模式从而达到利润的最大化,如何对商业模式进行改变也就成了最大的课题。首先,从不同种类电动机的结构入手,分析不同零件的构成材料与回收方式,找到最适合再制造的零件;然后,对目前电动机再制造的设计、检测、拆卸等环节进行综述,并总结目前针对电动机定子、转子、铁芯、绕组和机械部件的再制造方法;最后,对目前再制造企业的商业模式和市场环境进行梳理,分析目前再制造企业所面临的问题,并针对所存在的问题进行展望,以期为我国电动机再制造研究和电动机再制造企业的发展提供参考。

“19577”现代高效能应用型教学理论与实践研究报告

“19577”现代高效能应用型教学是应用型高校培养高素质应用型人才的教学理论与实践模式。“1”指“顶天立地,应用创新”的应用型大学教学理念;“9”指本理论与实践模式下的教学目标系统、教学领导系统、管理与服务系统、应用型课堂教学系统、实训和实验系统、应用性课外活动与竞赛系统、应用型教学督导评价系统、产教融合的实习与就业系统和蓬勃发展的文化系统9个子系统;“5”是健康心理与积极人格教育、专业科技赋能教育、现代工匠精神教育、实践育人教育和现代素养教育5种有特色和针对性的教育;两个“7”分别是指以需求为导向、以学生为中心、以应用为主线、以现代化为主题、以创新为重点、以蓬勃发展的文化为生态、以高适应力高应用力高创造力高合作力和高幸福感“5高”为师生发展特征的7大策略和7个重要品格。“19577”现代高效能应用型教学理论与实践具有普遍的启发、引领与参考价值。

财政拨款项目仪器设备购置生命周期协同管理模式探讨

如何充分利用财政拨款项目资金,合理配置诊疗、科研等专业设备,在保障项目进度的同时,做好仪器设备选型、论证等调研分析工作,规范采购流程,提高财政拨款项目仪器设备购置工作质效,一直是困扰业界的主要问题。通过广泛调研发现财政拨款项目仪器设备购置工作中存在的具体问题包括采购制度不完善、采购流程不规范、可行性论证不充分、需求调研不充分、采购执行进度控制困难、安装就位验收困难。借鉴生命周期理论和协同管理理论,总结某口腔专科医院在国家财政专项仪器设备购置经验,构建生命周期分段式横纵向协同管理模式,解决配置不合理、采购不规范、项目进度慢的问题;探讨进一步提高国家财政拨款项目仪器设备购置工作质效,加强医院诊疗科研能力,全面提升医院高质量发展效能的科学方法。