Genetic algorithm for balancing reconfigurable machining lines

We consider the problem of designing a reconfigurable machining line. Such a line is composed of a sequence of workstations performing specific sets of operations. Each workstation is comprised of several identical CNC machines (machining centers). The line is required to satisfy the given precedence order, inclusion, exclusion and accessibility constraints on the given set of operations. Inclusion and exclusion are zoning constraints which oblige or forbid certain operations to be performed on the same workstation. The accessibility constraints imply that each operation has a set of possible part positions under which it can be performed. All the operations performed on the same workstation must have a common part position. Workstation times are computed taking into account processing and setup times for operations and must not exceed a given bound. The number of CNC machines at one workstation is limited, and the total number of machines must be minimized. A genetic algorithm is proposed. This algorithm is based on the permutation representation of solutions. A heuristic decoder is suggested to construct a solution from a permutation, so that the output solution is feasible w.r.t. precedence, accessibility, cycle time, and exclusion constraints. The other constraints are treated with a penalty approach. For a local improvement of solutions, a mixed integer programming model is suggested for an optimal design of workstations if the order of operations is fixed. An experimental evaluation of the proposed GA on large scale test instances is performed.     

Minimal-dot plot: “Old tale in new skin” about sequence comparison

The authors propose a simple version of the dot-plot scheme to be used in the case when the distances between sequence elements may take more than two values. The method is applicable, in particular, to the case of the sequences of large-length windows when the sets of distance values are continuous. The proposed technique is simple to implement and the results can produce readable maps for further analysis. To illustrate its potentialities, the method has been applied to the comparison of genomic sequences. The asymmetry in the number of direct and reverse tracks for the Homo sapience genome has been discovered.     

Sequence Structure,Morphology and Viscosity Behavior of 3,3‐bis(azidomethyl) Oxetane‐tetrahydrofuran Random Copolyether

In order to reveal the relationship between 3,3‐bis(azidomethyl) oxetane‐tetrahydrofuran copolyether (P(BAMO‐THF)) microstructure and its macro properties, the segment sequence structure of a kind of P(BAMO‐THF) was characterized using quantitative ¹³C‐NMR analysis. It was found that the P(BAMO‐THF) is composed of equimolar comonomers whose randomness factor (R) is 1.09, belonging to a quasi‐ideal random copolymer. Combining DSC and polarizing optical microscopy, it was verified that the thermal‐effect between 28 °C and 41 °C attributes to the melting of the P(BAMO‐THF)spherulites. Using WAXRD, it was suggested that the aggregation of BAMO micro‐blocks among P(BAMO‐THF) polymeric chains causes the formation of spherulites. The viscosity measurement clearly demonstrated that, below 30 °C or above 40 °C, the P(BAMO‐THF) viscosities change slowly as a function of temperature. Conversely, between 30 °C and 40 °C, its viscosities sharply decline with the increase in temperature because of the changes in its morphology.     

卧式车床序轴式短链主传动的设计

基于越轴式短链主传动的简要分析，提出了序轴式短链主传动的设计方案。该方案的变速范围大、变速级数多、轴向尺寸小，并且兼有短链和短支距传动的特点。     

汽车喷漆批次重组建模与优化

焊接车间按车型组织生产,同一车型又有多种颜色。按焊接生产序列进行喷漆作业,必然导致油漆喷头的反复冲洗和频繁更换,不仅增大了生产成本,还加剧了环境污染。基于某汽车厂喷漆车间的作业现状,进行喷漆生产序列重构。采用混合整型线性规划方法,以油漆喷头更换次数最小化为目标,在缓存区入口和出口处分别建立了批次分离和批次合并的混合整型线性规划模型,并用GAMS/Cplex完成其求解。结果表明,利用该方法对车辆序列进行优化后,喷头更换和冲洗次数可减少约(68~92)%,年度可节约成本1088.64万元。     

机器人在压缩机壳体冲孔上的应用

在压缩机壳体冲孔的工艺中引入机器人技术,根据工艺时序图及机器人的模拟动作时间设计了机器人动作节拍;对实际生产时两台机器人的分工协作设计了干涉区,以避免碰撞;通过修改机器人夹爪设计和在伺服马达处加装散热风扇,解决轴马达温度过热问题。通过应用机器人提高了生产效率,改善了劳动条件。为机器人在自动化生产方面进行了一些有益的探索。     

松辽盆地东南隆起区登娄库组层序地层研究

本文综合采用层序地层学等最新理论和方法,运用地震、测井、岩芯等分析资料,对东南隆起区登娄库组地层的层序地层格架进行了深入细致的分析和研究,对今后该区油气勘探与开发及井位部署具有实际的指导意义。     

基于自适应采样的移动WSN定位算法

节点自定位是无线传感器网络的关键技术之一。当前对无线传感器网络定位的研究主要集中静态节点定位,移动无线传感器网络定位研究相对较少。研究了基于序列蒙特卡罗方法的移动无线传感器网络定位。针对蒙特卡罗定位采用固定样本数,计算量大的缺点,根据蒙特卡罗定位盒（MCB）算法的锚盒子大小动态设置样本数,提出一种自适应采样蒙特卡罗盒定位算法。仿真表明,该算法在保持定位精度的同时有效地减小了采样次数,节约了计算量。     

Time-varying AR modeling and adaptive IIR notch filter for anti-jamming DSSS receiver

Using Time-Varying AR (TVAR) model and adaptive notch filter is a new method for the non-stationary jammer suppression in Direct Sequence Spread Spectrum (DSSS). The performance of TVAR model for Instantaneous Frequency (IF) estimation will be affected by some factors such as basis functions. Focusing on this problem, the optimal basis function of TVAR model for the IF estimation of the LFM signal is obtained in this paper. Besides the depth and width of notching, the phase properties of notch filter affect the Signal-to-Interference plus-Noise Ratio (SINR) of correlation output to the narrowband jammer suppression in DSSS, in response to the problem the closed solution of correlation output SINR improvement has been derived when a single frequency jammer passes through direct IIR notch filter, and its performance has been compared with those of five coefficient FIR filters. Later, a novel method for LFM jammer suppression based on Fourier basis TVAR model and direct IIR notch filter is proposed. The simulation results show the effectiveness of the proposed method.     

Multi-layer floorplanning for stacked ICs: Configuration number and fixed-outline constraints

3-D (stacked device layers) ICs can significantly alleviate the interconnect problem coming with the decreasing feature size and is promising for heterogeneous integration. In this paper, we concentrate on the configuration number and fixed-outline constraints in the floorplanning for 3-D ICs. Extended sequence pair, named partitioned sequence pair (in short, P-SP), is used to represent 3-D IC floorplans. We prove that the number of configuration of 3-D IC floorplans represented by P-SP is less than that of planar floorplans represented by sequence pair (SP) and decreases as the device layer number increases. Moreover, we applied the technique of block position enumeration, which have been successfully used in planar fixed-outline floorplanning, to fixed-outline multi-layer floorplanning. The experimental results demonstrate the efficiency and effectiveness of the proposed method.