Experiments with a hybrid interior point/combinatorial approach for network flow problems

Interior point (IP) algorithms for Min Cost Flow (MCF) problems have been shown to be competitive with combinatorial approaches, at least on some problem classes and for very large instances. This is in part due to availability of specialized crossover routines for MCF; these allow early termination of the IP approach, sparing it with the final iterations where the Karush Kuhn-Tucker (KKT) systems become more difficult to solve. As the crossover procedures are nothing but combinatorial approaches to MCF that are only allowed to perform few iterations, the IP algorithm can be seen as a complex ‘multiple crash start’ routine for the combinatorial ones. We report our experiments of allowing one primal-dual combinatorial algorithm to MCF to perform as many iterations as required to solve the problem after being warm-started by an IP approach. Our results show that the efficiency of the combined approach critically depends on the accurate selection of a set of parameters among very many possible ones, for which designing accurate guidelines appears not to be an easy task; however, they also show that the combined approach can be competitive with the original combinatorial algorithm, at least on some ‘difficult’ instances.     

A hybrid intelligent system for medical data classification

In this paper, a hybrid intelligent system that consists of the Fuzzy Min–Max neural network, the Classification and Regression Tree, and the Random Forest model is proposed, and its efficacy as a decision support tool for medical data classification is examined. The hybrid intelligent system aims to exploit the advantages of the constituent models and, at the same time, alleviate their limitations. It is able to learn incrementally from data samples (owing to Fuzzy Min–Max neural network), explain its predicted outputs (owing to the Classification and Regression Tree), and achieve high classification performances (owing to Random Forest). To evaluate the effectiveness of the hybrid intelligent system, three benchmark medical data sets, viz., Breast Cancer Wisconsin, Pima Indians Diabetes, and Liver Disorders from the UCI Repository of Machine Learning, are used for evaluation. A number of useful performance metrics in medical applications which include accuracy, sensitivity, specificity, as well as the area under the Receiver Operating Characteristic curve are computed. The results are analyzed and compared with those from other methods published in the literature. The experimental outcomes positively demonstrate that the hybrid intelligent system is effective in undertaking medical data classification tasks. More importantly, the hybrid intelligent system not only is able to produce good results but also to elucidate its knowledge base with a decision tree. As a result, domain users (i.e., medical practitioners) are able to comprehend the prediction given by the hybrid intelligent system; hence accepting its role as a useful medical decision support tool.     

溪源泄洪洞出口处闽江设计水位分析研究

溪源泄洪洞出口位于闽江之上,为分析泄洪洞出口处的设计水位,采用设计流量和水位流量关系推求法及实测水位资料推求法两种方法对工程设计水位进行计算,经过合理性分析,工程所在地近年水位变化剧烈,采用设计流量和水位流量关系推求法更符合现状情况,为工程建设提供可靠的设计成果。     

化学灌浆在输水隧洞渗漏处理中的运用

福清市闽江调水工程输水隧洞,原地下水较活跃,后经水泥灌浆,堵住大部分水,但渗漏现象还比较严重,难以靠单一的水泥灌浆彻底堵住渗漏,后经采用PU4水溶性聚氨酯对漏水点进行化学灌浆取得了较好的止水效果。PU4水溶性聚氨酯是一种单组份灌浆材料,其遇水后自行分散、乳化、发泡,立即进行聚合反应,聚合后的固结体有良好的延伸性、弹性及抗渗性,体现了弹性止水和以水止水的双重功能。可供类似工程参考。     

闽学大师朱熹与兵部侍郎福清林栗辨易探究

朱熹是闽学代表人物,其《周易本义》成为元明清三代开科取士的教科书。林栗是宋代福州福清的名宦,官至兵部侍郎。但二人在易学思想上意见分歧,朱熹为宋易突出代表,对宋易邵雍先天之学推崇备至;林栗重视易学重象之传统,反对邵雍先天之学,而又赞成宋代流行的河图洛书之说。朱熹林栗二人辨易,展现了宋代汉易、宋易交糅纷呈的状况,也反映了闽学在争鸣中不断前进的历史事实。朱熹林栗二人辨易发展为相互讦奏,为一大憾事。但平心而论,《宋史》对林栗论定有失偏颇,林栗仍不失＂为时直臣＂。     

GB/T 12706对低压电力电缆护套厚度的控制及应用

对电力电缆外护套厚度的检验若控制不当，就会增加操作难度和产品成本。正确控制电力电缆外护套的平均厚度和最小厚度，对产品质量控制、生产效率提高、降低成本增加效益都具有非常现实的意义。     

A Min–Max multiregulator system with stability analysis for aeroengine propulsion control

Stability analysis is an essential issue in Min–Max multiregulator control strategy for commercial aircraft engines. In this paper, a Min–Max selector scheme along with a stability analysis method is provided for aeroengine propulsion control. It is assumed that the main regulator is a dynamic compensator and the limit regulators are constant gains. The regulators are determined in such a way that the individual control loops are stable. However, due to the switching nature of Min–Max structure, the stability of single loops does not necessarily ensure the overall system stability. In order to analyze the stability of the presented Min–Maxapproach, the architecture of the control system is transformed into the canonical form of Lure’s system and the condition for absolute stability is specified using Multivariable Circle Criterion. The theoretical results can also be applied to investigate the stability of min-only or max-only schemes. Afterwards, using the provided methodology, the global asymptotic stability is proved for the control system of a high bypass two-spool turbofan engine and the performance of the designed Min–Max controller in tracking a desired fan speed and limit protection in fault-free and fault tolerant situations is compared with the well-known Min–Max/SMC approach.     

A modified Min Sum decoding algorithm based on LMMSE for LDPC codes

A new modified Min Sum decoding algorithm based on parameter estimation theory for Low Density Parity Check (LDPC) codes is presented in this paper. First, Linear Minimum Mean Square Error (LMMSE) estimate criterion is used to model the magnitude of check-to-variable message and calculate estimated parameters, furthermore the golden section search algorithm is used to speed up getting the boundary, with which the parameters can be determined. Then, the parameters are modified further on the basis of the relationship between the iteration number and the estimated parameters. Finally, the same estimated parameters are used for different signal to noise ratio (SNR) to ensure the decoding performance and reduce the hardware complexity. The simulation results show that a gain of 0.3–0.5 dB can be achieved in comparison with other kinds of modified Min Sum algorithms, which is very close to that of BP algorithm. What's more, the algorithm has the following characteristics: low computation complexity, small decoding delay, easiness of calculation for estimated parameters, and simplicity in hardware implementation.     

TYIN tegnestue Architects. Integrating On-Site Education and Practice

Founded by Andreas Grøntvedt Gjertsen and Yashar Hanstad, TYIN tegnestue Architects grew out of an initiative to provide sleeping accommodation for an orphanage in Thailand when the principals were only third-year architecture students. Norwegian architect Lisbet Harboe explains how the student-architects built up a practice while in schools by refocusing their studies and those of their peers on learning through their own experiences of construction.     

福州闽江——乌龙江岸线变化及稳定性分析

采用福州市2000年、2004年、2009年有代表性的卫星影像图进行对比,分析其岸线的变化情况。结合定性与定量分析将岸坡稳定性程度划分为四个等级,将闽江-乌龙江岸坡稳定性进行分段分级,对影响闽江-乌龙江岸坡稳定性的地质因素、水动力条件及人为因素进行了探讨,最后提出了若干岸坡治理的有效措施。