奋力前行、创新不止——北工大软件园掠影

北京作为中国软件之都，软件产业销售收入连续8年居全国第一位，这些与北京软件产业基地和几大软件园的发展息息相关的。在这些高新技术园区中，唯一位于京城南部，与北京工业大学、北京经济技术开发区交融为一体的就是北工大软件园。

建设北工大软件园 为发展首都软件产业作贡献

北京工业大学和北京经济技术开发区于2001年12月合作成立了"北京北工大软件园发展有限责任公司",承担北工大软件园建设任务.一、北京软件产业发展的重大意义1.软件产业成为国际竞争的焦点计算机软件在信息技术中具有核心和灵魂的作用.随着全球社会信息化和经济信息化的发展,软件产业已成为世界经济的新增长点.发达国家乃至众多发展中国家都把软件产业作为优先发展的战略性产业,作为国民经济中的支柱.它已成为国际竞争的焦点和战略制高点.近三年来,全球经济平均增长率仅为3.4%,而信息产业的平均增长率达10%,其中软件产业的平均增长率高达13%左右.2000年,全球软件产业总额为5960亿美元,比1999年的5274亿美元增长13%.

Path-Following Based on Nonlinear Model Predictive Control with Adaptive Path Preview

This paper presents a Nonlinear Model Predictive Controller(NMPC)for the path following of autonomous vehicles and an algorithm to adaptively adjust the preview distance.The prediction model includes vehicle dynamics,path following dynamics,and system input dynamics.The single-track vehicle model considers the vehicle’s coupled lateral and longitudinal dynamics,as well as nonlinear tire forces.The tracking error dynamics are derived based on the curvilinear coordinates.The cost function is designed to minimize path tracking errors and control effort while considering constraints such as actuator bounds and tire grip limits.An algorithm that utilizes the optimal preview distance vector to query the corresponding reference curvature and reference speed.The length of the preview path is adaptively adjusted based on the vehicle speed,heading error,and path curvature.We validate the controller performance in a simulation environment with the autonomous racing scenario.The simulation results show that the vehicle accurately follows the highly dynamic path with small tracking errors.The maximum preview distance can be prior estimated and guidance the selection of the prediction horizon for NMPC.

Evading strength−ductility trade-off of GH605 alloy using magnetic field-assisted undercooling treatment

Undercooling solidification under a magnetic field(UMF)is an effective way to tailor the microstructure and properties of Co-based alloys.In this study,by attributing to the UMF treatment,the strength−ductility trade-off dilemma in GH605 superalloy is successfully overcome.The UMF treatment can effectively refine the grains and increase the solid solubility,leading to the high yield strength.The main deformation mechanism in the as-forged alloy is dislocation slipping.By contrast,multiple deformation mechanisms,including stacking faults,twining,dislocation slipping,and their strong interactions are activated in the UMF-treated sample during compression deformation,which enhances the strength and ductility simultaneously.In addition,the precipitation of hard Laves phases along the grain boundaries can be obtained after UMF treatment,hindering crack propagation during compression deformation.

Ablation behaviour and mechanical performance of ZrB_(2)-ZrC-SiC modified carbon/carbon composites prepared by vacuum infiltration combined with reactive melt infiltration

The development of advanced aircraft relies on high performance thermal-structural materials,and carbon/carbon com-posites(C/C)composited with ultrahigh-temperature ceramics are ideal candidates.However,the traditional routes of compositing are either inefficient and expensive or lead to a non-uniform distribution of ceramics in the matrix.Compared with the traditional C/C-ZrC-SiC composites prepared by the reactive melt infiltration of ZrSi_(2),C/C-ZrB_(2)-ZrC-SiC composites prepared by the vacuum infiltration of ZrB_(2) combined with reactive melt infiltration have the higher content and more uniform distribution of the introduced ceramic phases.The mass and linear ablation rates of the C/C-ZrB_(2)-ZrC-SiC composites were respectively 68.9%and 29.7%lower than those of C/C-ZrC-SiC composites prepared by reactive melt infiltration.The ablation performance was improved because the volatilization of B_(2)O_(3),removes some of the heat,and the more uniformly distributed ZrO_(2),that helps produce a ZrO2-SiO2 continu-ous protective layer,hinders oxygen infiltration and decreases ablation.

Mechanism of high temperature oxidation of Inconel 625 superalloy with various solution and ageing heat treatment processes

The high-temperature oxidation behaviour of the Inconel 625 alloy at 950℃ was investigated after different ageing treatments.The effect of heat treatment on the oxidation behaviour of the alloy was analysed by characterizing the structure and elemental distribution before and after oxidation.The results reveal that the two ageing treatments at 650℃ for 500 h and at 750℃ for 400 h both reduced the oxidation mass gain.After oxidation at 950℃,an outer Cr_(2)O_(3) layer and inner Al_(2)O_(3) are identified as the main oxidation products.Moreover,Nb_(2)O_(5) andδ(Ni_(3)Nb)phases precipitated after oxidation.The ageing treatments cause the rapid generation of a dense Cr_(2)O_(3) layer on the surface,which prevents the diffusion of oxygen into the matrix,reduce the Al_(2)O_(3) inward growth depth,and improve the oxidation resistance of the alloy.

Versatile fluidity test model for cast superalloys and comparison between IN718 and IN939

A spiral fluidity test model of superalloys with 10 mm in height and 3 mm in thickness was designed to evaluate the fluidity of two distinct Ni-based superalloys IN718 and IN939.The factors influencing fluidity are ascertained through comparative analysis utilizing methodologies such as JMat Pro,differential scanning calorimetry and high-temperature confocal laser scanning microscopy.The results show that under identical testing conditions,the fluidity of the IN939 superalloy surpasses that of the IN718 superalloy.When subjected to the same temperature,the melt viscosity and surface tension of IN939 superalloy are considerably reduced relative to those of IN718 superalloy,which is beneficial to improving the melt fluidity.Furthermore,the liquidus temperature and solidification range for the IN939 superalloy are both smaller compared with those of the IN718 superalloy.This condition proves advantageous in delaying dendrite coherency,thereby improving fluidity.

Design and Verification for Dual⁃mode CDFS and High⁃Load Compressor with a Large Flow Regulation Range

This paper presents the design and verification of the dual-mode core driven fan stage(CDFS)and high-load compressor with a large flow regulation range.In view of the characteristics of large flow regulation range of the two modes and high average stage load coefficient,this paper investigates the design technology of the dual-mode high-efficiency compressor with a large flow regulation range and high-load compressor with an average stage load coefficient of 0.504.Building upon this research,the design of the dual-mode CDFS and four-stage compressor is completed,and three-dimensional numerical simulation of the two modes is carried out.Finally,performance experiment is conducted to verify the result of three-dimensional numerical simulation.The experiment results show that the compressor performance is improved for the whole working conditions by using the new design method,which realizes the complete fusion design of the CDFS and high-pressure compressor(HPC).The matching mechanism of stage characteristics of single and double bypass modes and the variation rule of different adjustment angles on performance are studied comprehensively.Furthermore,it effectively reduces the length and weight of compressor,and breaks through the key technologies such as high-load compressor with the average load factor of 0.504.These findings provide valuable data and a methodological foundation for the development of the next generation aeroengine.

Effects ofslip mode on microstructure evolution and compressive flow behavior of extruded dilute Mg−0.5Bi−0.5Sn−0.5Mn alloy

The influence of the slip mode on the microstructure evolution and compressive flow behavior at different strains in an extruded dilute Mg−0.5Bi−0.5Sn−0.5Mn alloy was analyzed through electron backscatter diffraction,X-ray diffraction,transmission electron microscopy,and hot compression tests.The results showed that at a low strain of 0.05,the basal,pyramidaland<c+a>slip modes were simultaneously activated.Nevertheless,at the middle stage of deformation(strain of 0.1,0.2 and 0.5),theslip mode was difficult to be activated and<c+a>slip mode became dominant.The deformation process between strains of 0.2 and 0.5 was primarily characterized by the softening effect resulting from the simultaneous occurrence of continuous dynamic recrystallization and discontinuous dynamic recrystallization.Ultimately,at strain of 0.8,a dynamic equilibrium was established,with the flow stress remaining constant due to the interplay between the dynamic softening brought about by discontinuous dynamic recrystallization and the work-hardening effect induced by the activation of the basalslip mode.

Gated Neural Network-Based Unsteady Aerodynamic Modeling for Large Angles of Attack

Modeling of unsteady aerodynamic loads at high angles of attack using a small amount of experimental or simulation data to construct predictive models for unknown states can greatly improve the efficiency of aircraft unsteady aerodynamic design and flight dynamics analysis.In this paper,aiming at the problems of poor generalization of traditional aerodynamic models and intelligent models,an intelligent aerodynamic modeling method based on gated neural units is proposed.The time memory characteristics of the gated neural unit is fully utilized,thus the nonlinear flow field characterization ability of the learning and training process is enhanced,and the generalization ability of the whole prediction model is improved.The prediction and verification of the model are carried out under the maneuvering flight condition of NACA0015 airfoil.The results show that the model has good adaptability.In the interpolation prediction,the maximum prediction error of the lift and drag coefficients and the moment coefficient does not exceed 10%,which can basically represent the variation characteristics of the entire flow field.In the construction of extrapolation models,the training model based on the strong nonlinear data has good accuracy for weak nonlinear prediction.Furthermore,the error is larger,even exceeding 20%,which indicates that the extrapolation and generalization capabilities need to be further optimized by integrating physical models.Compared with the conventional state space equation model,the proposed method can improve the extrapolation accuracy and efficiency by 78%and 60%,respectively,which demonstrates the applied potential of this method in aerodynamic modeling.

Improving comprehensive properties of Cu-11.9Al-2.5Mn shape memory alloy by adding multi-layer graphene carried by Cu_(51)Zr_(14)inoculant particles

In order to improve the comprehensive properties of the Cu-11.9Al-2.5Mn shape memory alloy(SMA),multilayer graphene(MLG)carried by Cu_(51)Zr_(14)inoculant particles was incorporated and dispersed into this alloy through preparing the preform of the cold-pressed MLG-Cu_(51)Zr_(14)composite powders.In the resultant novel MLG/Cu-Al-Mn composites,MLG in fragmented or flocculent form has a good bonding with the Cu-Al-Mn matrix.MLG can prevent the coarsening of grains of the Cu-Al-Mn SMA and cause thermal mismatch dislocations near the MLG/Cu-Al-Mn interfaces.The damping and mechanical properties of the MLG/Cu-Al-Mn composites are significantly improved.When the content of MLG reaches 0.2 wt.%,the highest room temperature damping of 0.0558,tensile strength of 801.5 MPa,elongation of 10.8%,and hardness of HV 308 can be obtained.On the basis of in-depth observation of microstructures,combined with the theory of internal friction and strengthening and toughening theories of metals,the relevant mechanisms are discussed.

硅场发射二极管阵列的实验研究

介绍了Ｐ型硅场发射二极管阵列的工艺与实验研究，并讨论了硅发射体表面薄氧化层对其伏安特性的影响。

基于多源数据的地铁站域活力评价方法研究

轨道交通因其运载量大、时间准、效率高等优势,成为人们出行的重要方式,同时也提高轨道交通站点周边公共空间的利用率。地铁站域更是人们交通出行与休闲生活的必要场所,因此提高地铁站域空间活力对轨道交通使用者的日常出行及生活质量的改善具有重要意义。以地铁站域活力为研究对象,提取站域活力的来源,基于多源数据对地铁站域活力的量化影响要素进行研究。

存量更新视角下市政设施复合化设计策略研究

随着城市更新行动的落实,市政设施与城市的融合问题越来越受到关注。从城市存量更新入手,针对市政设施周围的“空间消极”、对城市品质提升造成阻碍、缺乏与城市互动等问题,通过对国内外先进案例的剖析归纳,提出“复合化设计”理念,总结出“基于生态景观的复合”“基于文化精神的复合”“基于城市功能的复合”的策略,以期为缓解市政设施建设和城市发展之间的矛盾提供参考。

深孔钻导条耐用度的试验研究

在大量切削试验中发现深孔钻削TA_2钛合金(孔φ65>1000)时,钻头(内排屑三齿可转位刀片式)导条的磨损均比刀片的磨损严重得多。磨损的主要表现形式为粘结磨损、扩散磨损和机械磨损。其中,粘结磨损为主要磨损方式。此外,导条的崩块与裂纹也是钻头失效的原因。既然导条磨损是深孔钻削时影响钻头使用寿命的主要因素,那么,如何减小深孔钻头导条磨损,提高导条耐用度,便成为提高钻头使用寿命的主要问题。为此,从几个方面进行试验研究,寻找出规律。

钛合金深孔钻削刀具破损和磨损研究

对钻削钛合金内排屑深孔钻进行了失效研究.探讨了导致钻头的失效主要方面、因素和机理,提出了改进措施.

SMC6200/6200A系列单片机开发(一)

ＥＰＳＯＮ公司ＳＭＣ６２系列单片机的硬件、软件开发工具及其使用方法：包括内电路仿真器、评价板、交叉汇编器、乐音汇编器、功能选项生成器等。

SMC6200/6200A系列单片机开发(二)

ＳＭＣ６２００／６２００Ａ系列单片机开发（二）ＥＰＳＯＮ单片机北工大技术培训中心（１０００２２）张俊谟接第３期）②评价板的功能。ＥＶＡ６２ｘｘ有以下基本功能：运行功能：装入含应用程序的ＥＰＲＯＭ，并运行该程序。单步功能：单步执行指令，每条指令的执行后...

测试码生成简述

测试码生成简述中国科学院计算所ＣＡＤ开放实验室梁业伟北京计算机学院一、测试基本概念数字电路的测试有电性能测试和逻辑测试。逻辑测试的目的是检查电路的逻辑性能是否完好，是否存在逻辑故障。逻辑性能不完好，有错误，则说明存在逻辑故障。这里谈的是逻辑性能，不是...