Multi-segment and Multi-ply Overlapping Process of Multi Coupled Activities Based on Valid Information Evolution

Complex product development will inevitably face the design planning of the multi-coupled activities, and overlapping these activities could potentially reduce product development time, but there is a risk of the additional cost. Although the downstream task information dependence to the upstream task is already considered in the current researches, but the design process overall iteration caused by the information interdependence between activities is hardly discussed; especially the impact on the design process＇ overall iteration from the valid information accumulation process. Secondly, most studies only focus on the single overlapping process of two activities, rarely take multi-segment and multi-ply overlapping process of multi coupled activities into account; especially the inherent link between product development time and cost which originates from the overlapping process of multi coupled activities. For the purpose of solving the above problems, as to the insufficiency of the accumulated valid information in overlapping process, the function of the valid information evolution （VIE） degree is constructed. Stochastic process theory is used to describe the design information exchange and the valid information accumulation in the overlapping segment, and then the planning models of the single overlapping segment are built. On these bases, by analyzing overlapping processes and overlapping features of multi-coupling activities, multi-segment and multi-ply overlapping planning models are built; by sorting overlapping processes and analyzing the construction of these planning models, two conclusions are obtained： （1） As to multi-segment and multi-ply overlapping of multi coupled activities, the total decrement of the task set development time is the sum of the time decrement caused by basic overlapping segments, and minus the sum of the time increment caused by multiple overlapping segments; （2） the total increment of development cost is the sum of the cost increment caused by all overlapping process. And then, based on overlapping degree analysis of these planning models, by the V1E degree function, the four lemmas theory proofs are represented, and two propositions are finally proved： （1） The multi-ply overlapping of the multi coupled activities will weaken the basic overlapping effect on the development cycle time reduction （2） Overlapping the multi coupled activities will decrease product development cycle, but increase product development cost. And there is trade-off between development time and cost. And so, two methods are given to slacken and eliminate multi-ply overlapping effects. At last, an example about a vehicle upper subsystem design illustrates the application of the proposed models; compared with a sequential execution pattern, the decreasing of development cycle （22%） and the increasing of development cost （3%） show the validity of the method in the example The proposed research not only lays a theoretical foundation for correctly planning complex product development process, but also provides specific and effective operation methods for overlapping multi coupled activities.

Enhancement of thermal rectification by asymmetry engineering of thermal conductivity and geometric structure for multi-segment thermal rectifier

Thermal rectification is an exotic thermal transport phenomenon,an analog to electrical rectification,in which heat flux along one direction is larger than that in the other direction and is of significant interest in electronic device applications.However,achieving high thermal rectification efficiency or rectification ratio is still a scientific challenge.In this work,we performed a systematic simulation of thermal rectification by considering both efforts of thermal conductivity asymmetry and geometrical asymmetry in a multi-segment thermal rectifier.It is found that the high asymmetry of thermal conductivity and the asymmetry of the geometric structure of multi-segment thermal rectifiers can significantly enhance the thermal rectification,and the combination of both thermal conductivity asymmetry and geometrical asymmetry can further improve thermal rectification efficiency.This work suggests a possible way for improving thermal rectification devices by asymmetry engineering.

DDoS Defense Algorithm Based on Multi-Segment Timeout Technology

Through the analysis to the DDoS（distributed denial of service） attack, it will conclude that at different time segments, the arrive rate of normal SYN （Synchronization） package are similar, while the abnormal packages are different with the normal ones. Toward this situation a DDoS defense algorithm based on multi-segment timeout technology is presented, more than one timeout segment are set to control the net flow. Experiment results show that in the case of little flow, multi-segment timeout has the ability dynamic defense, so the system performance is improved and the system has high response rate.

A two-parameter multiple shooting method and its application to the natural vibrations of non-prismatic multi-segment beams

This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Bernoulli beams.The proposed algorithm,named as two-parameter multiple shooting method,is a new powerful numerical tool for calculating the natural frequencies and modes of multi-segment prismatic and non-prismatic beams with different boundary conditions.The impact of the axial force and additional point masses is also taken into account.Due to the fact that the method is based directly on the fourth-order ordinary differential equation,the structures do not have to be divided into many small elements to obtain an accurate enough solution,even though the geometry is very complex.To verify the proposed method,three different examples are considered,i.e.,a three-segment non-prismatic beam,a prismatic column subject to non-uniformly distributed compressive loads,and a two-segment beam with an additional point mass.Numerical analyses are carried out with the software MATHEMATICA.The results are compared with the solutions computed by the commercial finite element program SOFiSTiK.Good agreement is achieved,which confirms the correctness and high effectiveness of the formulated algorithm.

High-power and high optical conversion efficiency diode-end-pumped laser with multi-segmented Nd：YAG/Nd：YVO-4

A novel flat-flat resonator consisting of two crystals（Nd：YAG ＋ Nd：YVO4） is established for power scaling in a diode-end-pumped solid-state laser. We systematically compare laser characteristics between multi-segmented（Nd：YAG ＋ Nd：YVO4） and conventional composite（Nd：YAG ＋ Nd：YAG） crystals to demonstrate the feasibility of spectral line matching for output power scale-up in end-pumped lasers. A maximum continuous-wave output power of 79.2 W is reported at 1064 nm, with Mx2= 4.82, My2= 5.48, and a pumping power of 136 W in the multi-segmented crystals（Nd：YAG ＋ Nd：YVO4）. Compared to conventional composite crystals（Nd：YAG ＋ Nd：YAG）, the optical-optical conversion efficiency of multi-segmented crystals（Nd：YAG ＋ Nd：YVO4） from 808 nm to 1064 nm is enhanced from 30% to 58.8%,while the laser output sensitivity as affected by the diode-laser temperature is reduced from 55% to 9%.

Multi-segmented nanowires for vortex magnetic domain wall racetrack memory

A vortex domain wall's(VW) magnetic racetrack memory's high performance depends on VW structural stability,high speed, low power consumption and high storage density. In this study, these critical parameters were investigated in magnetic multi-segmented nanowires using micromagnetic simulation. Thus, an offset magnetic nanowire with a junction at the center was proposed for this purpose. This junction was implemented by shifting one portion of the magnetic nanowire horizontally in the x-direction(l) and vertically(d) in the y-direction. The VW structure became stable by manipulating magnetic properties, such as magnetic saturation(M_(4)) and magnetic anisotropy energy(K_(u)). In this case, increasing the values of M_(4) ≥ 800 kA/m keeps the VW structure stable during its dynamics and pinning and depinning in offset nanowires,which contributes to maintenance of the storage memory's lifetime for a longer period. It was also found that the VW moved with a speed of 500 m/s, which is desirable for VW racetrack memory devices. Moreover, it was revealed that the VW velocity could be controlled by adjusting the offset area dimensions(l and d), which helps to drive the VW by using low current densities and reducing the thermal-magnetic spin fluctuations. Further, the depinning current density of the VW(J_(d)) over the offset area increases as d increases and l decreases. In addition, magnetic properties, such as the M_(4) and K_(u),can affect the depinning process of the VW through the offset area. For high storage density, magnetic nanowires(multisegmented) with four junctions were designed. In total, six states were found with high VW stability, which means three bits per cell. Herein, we observed that the depinning current density(J_(d)) for moving the VW from one state to another was highly influenced by the offset area geometry(l and d) and the material's magnetic properties, such as the M_(4) and K_(u).

Double tractors swing microendoscopic discectomy technique for multi-segmental lumbar disc herniation

Objective To evaluate the effect of double tractors swing microendoscopic discectomy technique in multisegmental lumbar disc herniation.Methods From December 2006 to November 2009,153 patients with multisegmental lumbar disc herniation

Three-dimensional numerical analysis on combustion performance and flow of hybrid rocket motor with multi-segmented grain

This paper presents the combustion characteristics in hybrid rocket motors with multisegmented grain through three-dimensional numerical simulations.Multi-segmented grain is composed of several thin grains with two or more ports.The numerical model consists of Navier-Stokes equations with turbulence,solid fuel pyrolysis,chemical reactions,a fluid–solid coupling model and a regression rate model.The simulations adopt 90%Hydrogen Peroxide(HP)and PolyEthylene(PE)as the propellant combination.The effects of the rotation,port number,fuel grain segment number and mid-chamber length on the flow field and combustion performances are analyzed.The results indicate that the multi-segmented grain configuration can strengthen the flow field,and the regression rate and combustion efficiency are enhanced.Take the cases with two grain segments and three ports for example,the regression rate is increased by 32.4%-45.1%and the combustion efficiency increases by 6%-8.6%in different rotation angles.

Optimizing the cleanliness in multi-segment disk amplifiers based on vector flow schemes

The objective of maintaining the cleanliness of the multi-segment disk amplifier in Shenguang-II(SG-II) is to reduce laser-induced damage for optics. The flow field of clean gas, which is used for the transportation of contaminant particles,is a key factor affecting the cleanliness level in the multi-segment disk amplifier. We developed a gas–solid coupling and three-dimensional flow numerical simulation model. The three-dimensional and two-phase flow model is verified by the flow-field smog experiment and the particle concentration measurement experiment with the 130-disk amplifier in SG-II. By optimizing the boundary conditions with the same flow rate, the multi-inlet vector flow scheme can not only effectively reduce the purging time, but also prevent the reverse diffusion of contaminant particles in the multi-segment disk amplifier and the deposition of contaminant particles on the surface of the Nd:glass.

Multi-segment linear gradient optimization strategy based on resolution map in HPLC

Based on the mechanism of chromatographic retention (the relationship between the retention of solute and the mobile phase conditions) and method of resolution map, several methods of optimizing multi-segment linear gradient elution conditions were proposed according to the different separation requirements of various samples. These methods were verified using literature data. Moreover, the advantages and disadvantages of these methods were compared. It was proved that the third method is a fast optimization method which is capable of separating all the components with relatively high resolution.

A 14-bit wide temperature range differential SAR ADC with an on-chip multi-segment BGR

A 14-bit low power self-timed differential successive approximation（SAR） ADC with an on-chip multisegment bandgap reference（BGR） is described.An on-chip multi-segment BGR,which has a temperature coefficient of 1.3 ppm/℃and a thermal drift of about 100μV over the temperature range of -40 to 120℃is implemented to provide a high precision reference voltage for the SAR ADC.The Gray code form is utilized instead of binary form mode control to reduce substrate noise and enhance the linearity of the whole system.Self-timed bit-cycling is adopted to enhance the time efficiency.The 14-bit ADC was fabricated in a TSMC 0.13μm CMOS process. With the on-chip BGR,the SAR ADC achieves an SNDR of 81.2 dB（13.2 ENOB） and an SFDR of 85.2 dB with a conversion rate of 2 MS/s at room temperature and can keep an ENOB of more than 12 bits at a conversion rate of 2 MS/s over the temperature range from -40 to 120℃.

多尺度特征增强的街景绿色景观分割方法

针对街景图像中景观复杂多样且多种景观相互遮挡,绿色景观分割效果存在相似景观错分、边界分割模糊、细节丢失等问题,提出一种多尺度特征增强的城市绿色景观分割网络。在编码部分改进多尺度残差网络提取上下文信息以区分相似景观,同时构建多级特征聚合增强模块增强目标特征的边缘细节信息。增加双注意力机制,在局部特征上建模丰富的上下文联系。最后,将多级特征聚合增强模块同样引入解码器,并融合多层级特征来提高目标信息的恢复能力完善边缘信息。在公共街景数据集Cityscapes与自制数据集StreetData的消融实验表明,该网络与基础网络相比,平均交并比分别提高2.96%和5.57%。此外,在两个数据集上进行对比实验,该网络较对比模型平均交并比分别高1.25%~5.29%和1.52%~6.95%。定量分析与实验结果表明,该方法能够有效识别街景的绿色景观,实现高精度的城市绿色景观数据提取。

孔内多分段掏槽爆破数值模拟及实验研究

针对传统煤矿巷道掏槽爆破成本高、炮孔利用率低等问题,提出了一种孔内多分段掏槽爆破技术。通过采用ANSYS/AUTODYN数值模拟软件建立直眼掏槽、楔形掏槽和孔内多分段掏槽3组仿真模型,结合SPH算法进行仿真计算,对比分析了不同掏槽爆破模型的进尺效果,并针对孔内多分段掏槽爆破方法进行了现场缩比实验。研究表明:孔内多分段掏槽爆破模型理论上具有改善掘进面掏槽区自由面形态、破除岩石夹制力、增强爆破作用力等多种优点;仿真结果显示孔内多分段掏槽模型炮孔利用率可达97%,高于直眼掏槽和楔形掏槽;现场缩比实验结果表明,孔内多分段掏槽爆破进尺效果良好,最高可达100%,充分证明了孔内多分段掏槽爆破技术的优越性。

多期构造应力控制走滑断控储层发育机理与差异性研究——以塔里木盆地顺北地区为例

塔里木盆地顺北油气田发育典型走滑断控缝洞型储层。区别于受原始沉积相带控制的基质孔洞、受岩溶改造的洞穴等储集类型,走滑断控缝洞型储层的形成主要受断裂活动期构造应力导致的破裂作用控制。为研究走滑断裂多期活动背景下构造应力控制的断控储层发育机理与分布规律,综合应用野外、岩心、测录井、地震及钻井动态等资料,开展不同走滑断裂、同一走滑断裂沿走向不同部位、垂向不同层系断控储层发育特征表征,并结合应力场数值模拟手段开展多期构造应力恢复,预测断控储层发育的主要时期与分布规律。结果表明,走滑断裂活动期不同分段内部应力状态差异显著,其中拉分段内部以张应力为主,主要派生张性裂缝;压隆段内部以挤压应力为主,派生裂缝类型多样。顺北地区勘探目的层奥陶系一间房组顶面断控裂缝主要在加里东中期Ⅲ幕及加里东晚期—海西早期发育,海西中—晚期及之后裂缝基本不发育,且滑移距大的顺北18号断裂带较顺北1号断裂带派生裂缝开度、密度更高。走滑断控储层具有“簇状”结构特征,断裂活动期不同分段内部应力状态控制储层结构差异,拉分段“空腔”多,以“双簇”结构为主,核带规模大,压隆段核带结构多,以“多簇”结构为主,分割性强;走滑断裂活动期应力强度控制储集空间类型与规模,小型断裂储集空间以裂缝为主,大型断裂带发育核带结构,断控储层规模与断裂活动强度呈正相关关系;断控裂缝发育主要受断裂早期活动控制,晚期由于地层埋深增大,岩石不易破裂,新派生裂缝发育较少。

一种多段机翼水面起降地效无人机气动特性

为改善水面起降性能和气动性能,基于船身式机身、多段机翼和T尾融合设计思路,提出并设计了一种新型仿生式多段机翼地效无人机方案,采用N-S方程和K-Ω-SST湍流模型,详细研究了该型无人机在不同状态下的压力云图、压力系数及升阻特性。仿真结果表明,地效作用随离水高度的增加而减小,离水高度与平均几何弦长之比(高度弦长比H/c)接近1时,地效作用较为显著,无人机在离水高度0.2 m时,升力系数、升阻比分别提升21.91%和40.37%,阻力系数降低15.22%;对提出的多段机翼布局,地效飞行主要影响下表面压力系数和压力云图,下表面压力系数展向上由内向外正压增幅逐渐减小,弦向上前后缘附近压力系数较小,结合压力云图分析,地效对升力增幅的影响主要集中在中段和内段机翼下方区域;地效飞行可明显提高升力线斜率(H/c为1时提高了8.89%),迎角增加时升力系数增幅和阻力系数降幅均逐渐变大,升阻比增幅(H/c为1)在迎角2°后均达到26%以上;通过验证机的多轮水面起降和有、无地效飞行试验,证明设计方案具有优秀的气动性能和飞行性能,可为水质检测、水面地效运输、搜救侦察等提供应用平台。

底部填芯多节段预制拼装空心桥墩抗震性能试验研究

为提高预应力连接预制节段拼装桥墩的抗震性能及施工便捷性,设计了一种底部填芯多节段预制拼装空心桥墩并进行了抗震试验研究。提出了该新型预制节段拼装桥墩填芯高度设计方法,设计了底部填芯预制节段拼装桥墩缩尺模型并开展了拟静力试验测试。基于试验结果分析了该新型桥墩在水平循环往复作用下的裂缝发展过程、失效模式、滞回性能、延性性能、耗能能力及桥墩接缝的开口大小等抗震性能。研究结果表明:所发展的底部填芯多节段预制拼装空心桥墩的失效模式为底部节段混凝土局部压溃,但范围较小,所提填芯高度的设计方法可行,可以使桥墩实现预期失效模式。该新型桥墩具有较小的残余位移、优异的耗能能力与延性性能,这表明此桥墩具有优异的抗震性能。

MCFNet:融合上下文信息的多尺度视网膜动静脉分类网络

针对由于血管类间具有强相似性造成的动静脉错误分类问题,提出了一种新的融合上下文信息的多尺度视网膜动静脉分类网络(multi-scale retinal artery and vein classification network,MCFNet),该网络使用多尺度特征(multi-scale feature,MSF)提取模块及高效的全局上下文信息融合(efficient global contextual information aggregation,EGCA)模块结合U型分割网络进行动静脉分类,抑制了倾向于背景的特征并增强了血管的边缘、交点和末端特征,解决了段内动静脉错误分类问题。此外,在U型网络的解码器部分加入3层深度监督,使浅层信息得到充分训练,避免梯度消失,优化训练过程。在2个公开的眼底图像数据集(DRIVE-AV,LES-AV)上,与3种现有网络进行方法对比,该模型的F1评分分别提高了2.86、1.92、0.81个百分点,灵敏度分别提高了4.27、2.43、1.21个百分点,结果表明所提出的模型能够很好地解决动静脉分类错误的问题。

融合多尺度与边缘特征的道路提取网络

利用遥感影像提取道路对城市发展有重要意义。但是由于道路尺度多变、易被遮挡等因素,导致出现道路漏检、边缘不完整等问题。针对以上问题,本文提出了一种融合多尺度与边缘细节特征的道路提取网络(MeD-Net)。MeD-Net包括道路分割与边缘提取两部分。道路分割网络使用多尺度深层特征处理模块(MDFP),提取顾及全局与局部信息的多尺度特征,在卷积后使用组归一化优化模型训练;边缘提取网络利用细节引导融合算法提升深层边缘特征的细节信息,并利用注意力机制进行特征融合。为验证算法性能,本文利用Massachusetts道路数据集和青岛地区GF-2号道路数据集进行试验。试验表明,MeD-Net在两个数据集上交并比和F_(1)值均取得最高精度,能够提取不同尺度道路和更完整地保持道路边缘。

基于多平面分割和矩阵变换的航摄边坡点云滤波算法

点云滤波是实现地面点与非地面点分离,获取最真实地面点云的重要处理手段,是进行公路边坡点云灾害识别的基础.为了克服传统点云滤波算法在边坡场景下处理速度慢、结果精度低和误差大等问题,提出了基于多平面分割和矩阵变换的航摄边坡点云滤波算法.该方法首先利用基于曲率的区域生长算法对边坡进行多平面分割,得到多个边坡子点云;其次拟合得到边坡子点云平面模型,再利用旋转矩阵将边坡子点云进行空间转换至水平面;然后通过模拟布料下沉并设置距离阈值分离出非地面点;最后再次利用旋转矩阵的逆矩阵进行空间位置还原,进而得到滤波后的边坡点云.利用精细贴近仿地航线设计方法获取高精度点云模型以在不同的边坡场景下进行算法测试,并与其他传统滤波算法结果进行对比,结果表明:在所有的试验中,本文算法的总误差分别为7.11%、4.15%、1.45%、4.41%,在所有测试算法中最小;Kappa系数分别为0.77、0.90、0.96、0.90,在所有测试算法中最大.本文提出的算法在面对地形和植被情况复杂的边坡情景下,有着较高的准确性以及较强的适用性,为公路边坡点云滤波提供了新的解决方案.

基于特征掩膜的局部遮挡牛脸识别方法

随着智慧牧业的高速发展,牛脸识别已成为牛场智能化养殖的关键,但现实应用场景中牛脸遮挡问题较为严重,影响识别系统的性能。为此,提出一种遮挡物分割辅助牛脸识别的全新双分支网络结构。首先设计一种改进的轻量级U-Net遮挡物分割模型,通过加入深度可分离卷积和多尺度混合池化模块,有效提高分割网络对遮挡物的分割性能。为更好地衰减遮挡物对牛脸识别性能的影响,引入一种多级掩膜生成单元。以不同层级的遮挡分割为输入,构建识别网络不同阶段所对应的掩膜,通过掩膜运算在特征提取的各阶段有效消除遮挡造成的损坏特征信息。最后在自制数据集上进行算法有效性和实时性验证,并与多种最新的典型识别算法进行对比。实验结果表明,本文算法在遮挡牛脸数据集上平均准确率达86.34%,识别速度为54 f/s,且在不同程度遮挡的场景下,识别效果均优于FaceNet网络。