模块环境下的filter-SQP用于过程优化

Sequential Quadratic Programming(SQP) is the most efficient algorithm for nonlinear optimization.But a penalty function is usually used for linear search,causing some problems.Filter-SQP developed by Roger Fletcher and Sven Leyffer avoids using penalty function.In the view of filter-SQP,NLP problem has two objectives,one is minimizing objective function,the other is satisfying the constraints.The concept of filter is proposed on the basis of these two objectives.In this paper flowsheet optimization using filter-SQP in modular simulator environment was studied.Infeasible path strategy was used and the constraint function was composed of tear stream equation,specific design and unsatisfied inequality constraint.When filter could not find a step as the starting point of the next iteration,in order to avoid algorithm failure three strategies were used.They were restarting strategy,converging recycle strategy and feasible path strategy.A successive scaling strategy was proposed for filter-SQP to improve the efficiency of optimization.A case study of process optimization with filter-SQP was very encouraging.

Balanced Big Filter-模与Cousin复形

利用A-模M的深度depthAM以及Cousin复形C(D(A),M)的同调模对balancedbigfilter-模的特性进行了研究,并对C(D(A),M)的正合性进行了讨论。

条件线性高斯模型的Gauss Hermite filter-Kalman filter算法

针对条件线性高斯状态空间模型,提出了高斯厄密特滤波-卡尔曼滤波(Gauss Hermite filter-Kalmanfilter,GHF-KF)滤波算法。算法将模型中的条件线性状态方程代入观测方程,并融合线性状态的过程噪声和观测噪声,由GHF获得非线性状态的估计;再将非线性状态的估计均值代入线性状态方程与观测方程,由KF获得线性状态的估计;获得的非线性状态估计方差还用于修正由KF估计的线性状态,以提高精度。将GHF-KF算法应用于目标跟踪的仿真结果表明,与现有Rao-Blackwellized粒子滤波器RBPF相比,新方法在保证估计精度的同时,明显提高了实时性,计算时间仅约为RBPF的5%。

Filter-SQP算法在火炮发射动力学优化设计中的应用

火炮发射动力学优化设计是一类比较复杂的问题,传统的优化算法需要耗费大量时间计算火炮发射动力学模型。引入Filter-SQP算法,并对某车载火炮发射动力学模型进行了优化分析,通过与传统的SQP算法进行比较分析,表明该算法可以显著降低模型的计算次数,减少计算时间,因此,比较适用于解决火炮发射动力学优化问题。

A comparative study between flattening filter-free beams and flattening filter beams in radiotherapy treatment

Flattening filter-free(FFF) beams generated by medical linear particle accelerators(linacs) have recently been used in radiotherapy clinical practice.FFF beams have fundamental physical parameter differences with respect to standard flattening filter(FF) beams,such that the generally used dosimetric parameters and definitions are not always viable.This study investigates dosimetric parameters for use in the quality assurance of FFF beams generated by medical linacs in radiotherapy.The main characteristics of the photon beams are analyzed using specific data generated by a Varian True Beam linac having both FFF and FF beams of 6 and 10 MV(megavolt) energy,respectively.Definitions for dose profile parameters are suggested,starting from the renormalization of the FFF with respect to the corresponding FF beam.From this point,the flatness concept is translated into one of "un-flatness",and other definitions are proposed,maintaining a strict parallelism between FFF and FF parameter concepts.The quality controls used in establishing a quality assurance program when introducing FFF beams into the clinical environment are given,maintaining similarity to those used for standard FF beams,and recommendations for the introduction of FFF beams into clinical radiotherapy application for breast cancer patients are provided as an example for comparison between FFF and FF for dose distribution and coverage for a target volume.Although there are many advantages of using a FFF beam,especially for advanced radiotherapy techniques,there are a few limitations(e.g.,using a relatively higher energy photon beam for stereotactic radiotherapy(SRT),limited speed of current multileaf collimators(MLCs),and off-axis distance-dependent modulation in intensitymodulated radiation therapy(IMRT)) as well as challenges(e.g.,criteria for beam quality evaluation and penumbra,establishment of dosimetry methods,and consequences of photon target burn-up) that need to be addressed for establishing the FFF beam as a viable alternative to the FF beam.

Algebraic Attack on Filter-Combiner Model Keystream Generators

Algebraic attack was applied to attack Filter-Combintr model keystreamgenerators. We proposed the technique of function composition to improve the model, and the improvedmodel can resist the algebraic attack. A new criterion for designing Filter-Combiner model was alsoproposed: the total length I. of Linear Finite State Machines used in the model should be largeenough and the degree d of Filter-Combiner function should be approximate [L/2].

Alteration of Taste Acuity in Pediatric Cancer Patients after Treatment Completion: A Cross-Sectional Study Using a Filter-Paper Disc Method

Taste acuity of adult patients undergoing cancer treatment has been well investigated;however, studies of taste acuity after completion of cancer treatment are limited, particularly in children. This study aimed to assess taste acuity in pediatric cancer patients after treatment completion. Seventy-three patients who had completed cancer treatment (median age, 13 years;range, 7 - 18 years) and had not received any further treatment for at least 6 months were enrolled. Eighty-one healthy children (median age, 10 years;range, 8 - 19 years) served as controls. We determined the thresholds for four tastes (sweet, salty, sour, and bitter) using the filter-paper disc method. There was no significant difference in the thresholds of taste acuity for the four test solutions between the patient and control groups. The duration since treatment completion (<5 years vs. ≥5 years) had no significant impact on taste acuity for the four test solutions. The threshold for tasting salt was significantly higher in the group that had received chemotherapy + radiation and/or hematopoietic stem cell transplantation than that in the group that had received chemotherapy-only. Our results indicated that taste acuity after treatment completion in pediatric cancer patients was the same as that in healthy children. However, some treatment modalities were correlated with an impaired ability to taste salt. Gustatory test results should be considered while deciding nutritional support modalities after treatment completion in pediatric cancer patients.

Case Report: Anaplastic Astrocytoma Treated with Postoperative Radiotherapy Using Flattening Filter-Free Volumetric Arc Therapy (FFF-VMAT) during Pregnancy—Acceptable Fetal Dosimetry

Background: Postoperative irradiation for brain tumor in pregnant women is a matter of concern. Aim: We aimed to assess the safety of radiotherapy for brain tumors in pregnancy. We here report a successful treatment for anaplastic astrocytoma during pregnancy: surgery + postoperative irradiation. We wish to emphasize how we devised irradiation procedure to achieve both therapeutic effectiveness and safety to the fetus/infant. Case Presentation: A 34-year-old pregnant woman suffered with brain anaplastic astrocytoma. Tumor resection under craniotomy was performed with success. We decided to conduct postoperative radiotherapy at 25 weeks of gestation to reduce the risk of recurrence. We used a flattening filter-free volumetric arc therapy (FFF-VMAT) technique, which can achieve lower out-of-field dose than VMAT with a flattening filter or helical tomotherapy. We prescribed 60 Gy over 30 fractions. During actual beam delivery, surface and rectal dose to the patient (mother) were measured. The total fetal dose was estimated at 0.006 - 0.018 Gy, which is under the threshold set by the ICRP. A male healthy infant was born vaginally at the 37th week of pregnancy. The patient (mother) and the infant are healthy at the time of writing. Conclusion: FFF-VMAT is a good choice for brain tumors during pregnancy.

基于Filter-Hook技术的防火墙软件设计与实现

为了解决网络安全问题,设计了一个基于Filter-Hook技术的防火墙软件,该软件能够根据数据包过滤规则实现防火墙的功能。实验结果显示,该防火墙软件有效地改善了网络的安全性能。

A Filter-Based Pattern Search Method for Unconstrained Optimization

We discuss a filter-based pattern search method for unconstrained optimization in this paper. For the purpose to broaden the search range we use both filter technique and frames, which are fragments of grids, to provide a new criterion of iterate acceptance. The convergence can be ensured under some conditions. The numerical result shows that this method is practical and efficient.

Volumetric modulation arc radiotherapy with flattening filter-free beams compared with conventional beams for nasopharyngeal carcinoma:a feasibility study

There is increasing interest in the clinical use of flattening filter-free(FFF) beams.In this study,we aimed to investigate the dosimetric characteristics of volumetric modulated arc radiotherapy(VMAT) with FFF beams for nasopharyngeal carcinoma(NPC).Ten NPC patients were randomly selected to undergo a RapidArc plan with either FFF beams(RA-FFF) or conventional beams(RA-C).The doses to the planning target volumes(PTVs),organs at risk(OARs),and normal tissues were compared.The technical delivery parameters for RapidArc plans were also assessed to compare the characteristics of FFF and conventional beams.Both techniques delivered adequate doses to PTVs.For PTVs,RA-C delivered lower maximum and mean doses and improved conformity and homogeneity compared with RA-FFF.Both techniques provided similar maximum doses to the optic nerves and lenses.For the brain stem,spinal cord,larynx,parotid glands,oral cavity,and skin,RA-FFF showed significant dose increases compared to RA-C.The dose to normal tissue was lower in RA-FFF.The monitor units(MUs) were(536 ± 46) MU for RA-FFF and(501± 25) MU for RA-C.The treatment duration did not significantly differbetween plans.Although both treatment plans could meet clinical needs,RA-C is dosimetrically superior to RA-FFF for NPC radiotherapy.

A Filter-Based Uniform Algorithm for Optimizing Top-k Query in Distributed Networks

In this paper we propose a Filter-based Uniform Algorithm （FbUA） for optimizing top-κ query in distributed networks, which has been a topic of much recent interest. The basic idea of FhUA is to set a filter at each node to pre vent it from sending out the data with little chance to contrib ute to the top-κ result. FbUA can gain exact answers to top-κ query through two phrases of round trip communications between query station and participant nodes. The experiment results show that FbUA reduces network bandwidth consumption dramatically.

基于Filter-Hook Drive设计个人防火墙

结合Filter-Hook Driver的工作原理和特点,在Windows2000/XP下使用Filter-Hook Driver创建过滤函数,并利用设定好的过滤规则对访问的数据包进行过滤,实现防火墙的功能,给出程序实例。

Particle-filter-based walking prediction model for occlusion situations

In the field of mobile robotics,human tracking has emerged as an important objective for facilitating human-robot interaction.In this paper,we propose a particle-filter-based walking prediction model that will address an occlusion situation.Since the target being tracked is a human leg,a motion model for a leg is required.The validity of the proposed model is verified experimentally.

A FILTER-TRUST-REGION METHOD FOR LC^1 UNCONSTRAINED OPTIMIZATION AND ITS GLOBAL CONVERGENCE

In this paper we present a filter-trust-region algorithm for solving LC1 unconstrained optimization problems which uses the second Dini upper directional derivative. We establish the global convergence of the algorithm under reasonable assumptions.

The background calculation of the filter-fluorescer method

For the measurement of X-ray energy spectrum with filter-fluorescer method,the high energy tail at the rearward of response function is the main source of background.There are,traditionally,two techniques for measuring the background contributions:the same element Z for the fluorescer and filter,or the same element Z?1 for them.Using the formula of fluorescence intensity,and the elemental combinations of cobalt and iron,the backgrounds which the two techniques provide and the real one for measuring black-body radiation at equilibrium temperature of 7×106 K,were calculated.The results show that the Co-Co combination for the filter-fluorescer spectrometer can achieve better effect.A semi-quantitative analysis for the calculation results is discussed.

On the Solution of the Eigenvalue Complementarity Problem by a Line Search Filter-SQP Algorithm

In this paper, the Eigenvalue Complementarity Problem (EiCP) with real symmetric matrices is addressed, which appears in the study of contact problem in mechanics. We discuss a quadratic programming formulation to the problem. The resulting problems are nonlinear programs that can be solved by a line search filter-SQP algorithm.

用于加热卷烟的石蜡改性二醋酸纤维素降温滤嘴的制备与表征

以二醋酸纤维素滤棒为载体,以食品级石蜡为相变吸热材料,采用浸渍法制备了石蜡/醋纤降温滤棒,研究了石蜡熔点和负载量对加热卷烟主流烟气温度的影响,并采用热重/差热分析仪(TG/DTA)、傅里叶变换红外光谱仪(FT-IR)、差示扫描量热仪(DSC)和场发射扫描电子显微镜(SEM)等技术对石蜡/醋纤滤棒进行了表征。石蜡/醋纤滤棒是通过醋纤滤棒的吸附作用完成复合,在抽吸过程中具有良好的热稳定性,当52~#石蜡乳化液质量分数为60%时,即石蜡负载量为35 mg时,由石蜡/醋纤滤棒组成的三段式降温滤嘴对主流烟气具有显著的降温效果,可将主流烟气温度从68℃降低到42℃。

基于邻域采样的多任务图推荐算法

近年来,图神经网络(GNN)成为解决协同过滤的主流方法之一。它通过构建用户-物品图,模拟用户与物品的交互关系,并用GNN学习它们的特征表示。尽管现有在模型结构上的研究已取得了较大进展,但如何在图结构上更有效地进行负采样仍未有效解决。为此,提出一种基于邻域采样的多任务图推荐算法。该算法提出了一种基于GNN的邻域采样策略,该策略以每个用户为中心构建子图,将次高阶物品作为用户邻域采样的负样本,可以更有效地挖掘强负样本并提高采样质量。通过GNN对图结点进行信息聚合与特征提取,得到结点的最终嵌入表示。设计一种余弦边际损失来过滤部分冗余负样本,以有效减少采样过程中的噪声数据。同时,该算法引入了多任务策略对模型进行联合优化,以增强模型的泛化能力。在3个公开数据集上进行的大量实验表明,该算法在大多数情况下明显优于其他主流算法。

基于改进自适应陷波的双馈风电场时变次同步振荡抑制策略

双馈风电场经串补电容并网时,可能引发次同步控制相互作用(subsynchronous control interaction,SSCI),严重威胁系统安全稳定运行。通过在风机控制器中引入陷波器可有效阻断SSCI,然而固定参数陷波器难以适应实际系统中次同步振荡表现出的频率大范围时变特征。为解决这一问题,该文提出一种基于改进自适应陷波(adaptive notch filter,ANF)的双馈风电场时变次同步振荡抑制策略。首先,分析ANF安装于风机转子侧变流器(rotor-side converter,RSC)不同位置时对次同步振荡分量的阻断效果,确定ANF的最佳安装位置;其次,基于紧缩技术近似投影子空间跟踪算法(projection approximation subspace tracking based on the deflation technique,PASTd)在线获取次同步振荡信息,提出总体控制架构,设计基于量测数据辨识的ANF中心频率更新策略;最终,在考虑风速、风机台数、无功出力、电网拓扑变化等多种影响因素的情况下,验证控制策略对频率时变次同步振荡的抑制效果。与现有方法相比,所提控制策略不依赖于系统的准确数学模型,且具备较强的鲁棒性和适应性。