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Attribute Reduction with Test Cost Constraint 被引量:2
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作者 William Zhu 《Journal of Electronic Science and Technology》 CAS 2011年第2期97-102,共6页
In many machine learning applications,data are not free,and there is a test cost for each data item. For the economical reason,some existing works try to minimize the test cost and at the same time,preserve a particul... In many machine learning applications,data are not free,and there is a test cost for each data item. For the economical reason,some existing works try to minimize the test cost and at the same time,preserve a particular property of a given decision system. In this paper,we point out that the test cost one can afford is limited in some applications. Hence,one has to sacrifice respective properties to keep the test cost under a budget. To formalize this issue,we define the test cost constraint attribute reduction problem,where the optimization objective is to minimize the conditional information entropy. This problem is an essential generalization of both the test-cost-sensitive attribute reduction problem and the 0-1 knapsack problem,therefore it is more challenging. We propose a heuristic algorithm based on the information gain and test costs to deal with the new problem. The algorithm is tested on four UCI(University of California-Irvine) datasets with various test cost settings. Experimental results indicate the appropriate setting of the only user-specified parameter λ. 展开更多
关键词 cost-sensitive learning CONSTRAINT heuristic algorithm test cost
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Area-time associated test cost model for SoC and lower bound of test time
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作者 张金艺 翁寒一 +1 位作者 黄徐辉 蔡万林 《Journal of Shanghai University(English Edition)》 CAS 2011年第1期43-48,共6页
A novel test access mechanism (TAM) architecture with multi test-channel (TC) based on IEEE Standard 1500 is proposed instead of the traditional sub-TAM structure. The cost model of an area-time associated test an... A novel test access mechanism (TAM) architecture with multi test-channel (TC) based on IEEE Standard 1500 is proposed instead of the traditional sub-TAM structure. The cost model of an area-time associated test and the corresponding lower bound of system-on-chip (SoC) test time are established based on this TAM architecture. The model provides a more reliable method to control the SoC scheduling and reduces the complexity in related algorithm research. The result based on the area time associated test cost model has been validated using the ITC02 test benchmark. 展开更多
关键词 system-on-chip design for testability (SoC DriP) test cost test time lower bound
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Test Cost Optimization Using Tabu Search
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作者 Anu Sharma Arpita Jadhav +1 位作者 Praveen Ranjan Srivastava Renu Goyal 《Journal of Software Engineering and Applications》 2010年第5期477-486,共10页
In order to deliver a complete reliable software product, testing is performed. As testing phase carries on, cost of testing process increases and it directly affects the overall project cost. Many a times it happens ... In order to deliver a complete reliable software product, testing is performed. As testing phase carries on, cost of testing process increases and it directly affects the overall project cost. Many a times it happens that the actual cost becomes more than the estimated cost. Cost is considered as the most important parameter with respect to software testing, in software industry. In recent year’s researchers have done a variety of work in the area of Cost optimization by using various concepts like Genetic Algorithm, simulated annealing and Automation in generation of test data etc. This paper proposes an efficient cost effective approach for optimizing the cost of testing using Tabu Search (TS), which will provide maximum code coverage along with the concepts of Dijkstra’s Algorithm which will be implemented in Aspiration criteria of Tabu Search in order to optimize the cost and generate a minimum cost path with maximum coverage. 展开更多
关键词 Tabu SEARCH test cost OPTIMIZATION Dijikstra’s ALGORITHM
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An optimal stacking order for mid-bond testing cost reduction of 3D IC 被引量:2
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作者 Ni Tianming Liang Huaguo +4 位作者 Nie Mu Bian Jingchang Huang Zhengfeng Xu Xiumin Fang Xiangsheng 《Journal of Southeast University(English Edition)》 EI CAS 2018年第2期166-172,共7页
In order to solve the problem that the testing cost of the three-dimensional integrated circuit(3D IC)is too high,an optimal stacking order scheme is proposed to reduce the mid-bond test cost.A new testing model is bu... In order to solve the problem that the testing cost of the three-dimensional integrated circuit(3D IC)is too high,an optimal stacking order scheme is proposed to reduce the mid-bond test cost.A new testing model is built with the general consideration of both the test time for automatic test equipment(ATE)and manufacturing failure factors.An algorithm for testing cost and testing order optimization is proposed,and the minimum testing cost and optimized stacking order can be carried out by taking testing bandwidth and testing power as constraints.To prove the influence of the optimal stacking order on testing costs,two baselines stacked in sequential either in pyramid type or in inverted pyramid type are compared.Based on the benchmarks from ITC 02,experimental results show that for a 5-layer 3D IC,under different constraints,the optimal stacking order can reduce the test costs on average by 13%and 62%,respectively,compared to the pyramid type and inverted pyramid type.Furthermore,with the increase of the stack size,the test costs of the optimized stack order can be decreased. 展开更多
关键词 three-dimensional integrated circuit(3D IC) mid-bond test cost stacking order sequential stacking failed bonding
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Test sequencing problem arising at the design stage for reducing life cycle cost 被引量:3
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作者 Zhang Shigang Hu Zheng Wen Xisen 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2013年第4期1000-1007,共8页
Previous test sequencing algorithms only consider the execution cost of a test at the application stage. Due to the fact that the placement cost of some tests at the design stage is considerably high compared with the... Previous test sequencing algorithms only consider the execution cost of a test at the application stage. Due to the fact that the placement cost of some tests at the design stage is considerably high compared with the execution cost, the sequential diagnosis strategy obtained by previous methods is actually not optimal from the view of life cycle. In this paper, the test sequencing problem based on life cycle cost is presented. It is formulated as an optimization problem, which is non-deterministic polynomial-time hard (NP-hard). An algorithm and a strategy to improve its computational efficiency are proposed. The formulation and algorithms are tested on various simulated systems and comparisons are made with the extant test sequencing methods. Application on a pump rotational speed control (PRSC) system of a spacecraft is studied in detail. Both the simulation results and the real-world case application results suggest that the solution proposed in this paper can significantly reduce the life cycle cost of a sequential fault diagnosis strategy. 展开更多
关键词 AND/OR graph Heuristic search Life cycle cost Sequential fault diagnosis test sequencing problem
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一种将测试集嵌入到Test-per-Clock位流中的方法 被引量:1
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作者 刘铁桥 邝继顺 +1 位作者 蔡烁 尤志强 《计算机研究与发展》 EI CSCD 北大核心 2014年第9期2022-2029,共8页
集成电路测试方案的关键在于测试向量产生器的设计.传统的测试方法在测试向量生成、测试应用的过程中,没有充分利用测试数据位流来构建测试向量,从而造成了测试时间和存储开销的增加.为了减少测试成本,提出了一种基于test-per-clock模... 集成电路测试方案的关键在于测试向量产生器的设计.传统的测试方法在测试向量生成、测试应用的过程中,没有充分利用测试数据位流来构建测试向量,从而造成了测试时间和存储开销的增加.为了减少测试成本,提出了一种基于test-per-clock模式的内建自测试方法.通过对线性移位测试结构的分析,提出了一种递进式的反复测试生成方法:顺序求解输入位流,逆向精简,多次求解以获得更优值,最终将测试集以较小的代价嵌入到test-per-clock位流中.在测试应用时,只需存储求解后的最小输入流,通过控制线性移位的首位从而生成所需的测试集.实验结果表明,在达到故障覆盖率要求的前提下,能显著地减少测试应用时间和存储面积开销. 展开更多
关键词 内建自测试 test-per-clock 测试位流 测试生成 测试开销
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患者自费外购项目利用状况与医疗费用合理性评价的关联性分析
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作者 王云梦 邹冬冬 +3 位作者 周萍 蔡宇晖 陈淑雯 薛迪 《中国医院管理》 北大核心 2026年第2期33-36,共4页
目的分析上海市公立医疗机构门诊和住院患者自费外购项目利用状况及其与患者对医疗费用合理性评价的关联性。方法通过对2023年上海市公立医疗机构门诊和住院患者进行问卷调查,分析患者就医时自费外购药械、进行院外检测的实际状况。采... 目的分析上海市公立医疗机构门诊和住院患者自费外购项目利用状况及其与患者对医疗费用合理性评价的关联性。方法通过对2023年上海市公立医疗机构门诊和住院患者进行问卷调查,分析患者就医时自费外购药械、进行院外检测的实际状况。采用多分类logistic回归模型,分析自费外购药械和院外检测对患者“医院医疗费用合理”认同率的影响。结果2023年上海市公立医疗机构门诊和住院患者就诊中,自费外购药物率、自费外购器械率和自费院外检测率分别不足10%、7%和4%,门诊和住院患者对“医院医疗费用合理”的认同率分别为84.86%和95.75%。此外,自费外购药物和院外检测可降低门诊患者对“医院医疗费用合理”的认同率,自费外购药物和器械可降低住院患者对“医院医疗费用合理”的认同率。结论公立医疗机构应以价值为导向,减少患者不必要的自费外购药械、院外检测。 展开更多
关键词 自费 外购药物 器械检验检查 医疗费用
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误差在Cost-Sensitive分类中的应用 被引量:1
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作者 廖元秀 周生明 《广西师范大学学报(自然科学版)》 CAS 北大核心 2011年第2期110-113,共4页
针对使检查代价和误分类代价最小化的Cost-Sensitive学习,讨论误差在分类过程中的应用,提出一个带阈值的决策树,并给出一个带阈值的检查策略。在基于Cost-Sensitive学习的分类中,确定属性值所用到的检测手段和设备精度存在一定的误差值... 针对使检查代价和误分类代价最小化的Cost-Sensitive学习,讨论误差在分类过程中的应用,提出一个带阈值的决策树,并给出一个带阈值的检查策略。在基于Cost-Sensitive学习的分类中,确定属性值所用到的检测手段和设备精度存在一定的误差值,评估误分类代价更是有较大的误差。另外,很多分类问题并不要求达到百分之百的正确率,允许有一定的误差范围。把这些误差的边界看作是一个阈值,利用这种阈值来简化决策树的建立,改进检查策略的设计,提高分类效率。 展开更多
关键词 cost-Sensitive学习 分类代价 检查策略 分类误差范围 阈值
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Cost-Sensitive学习的一个新课题 被引量:2
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作者 周生明 廖元秀 《广西师范大学学报(自然科学版)》 CAS 北大核心 2007年第4期55-58,共4页
Cost-Sensitive学习注重分类过程中的各种代价,特别是误分类代价和属性代价。在Cost-Sensitive学习中还有一种代价对分类的总代价有较大影响,这种代价可称为分类延时代价,即延误分类而造成的代价。包含分类延时代价的Cost-Sensitive学习... Cost-Sensitive学习注重分类过程中的各种代价,特别是误分类代价和属性代价。在Cost-Sensitive学习中还有一种代价对分类的总代价有较大影响,这种代价可称为分类延时代价,即延误分类而造成的代价。包含分类延时代价的Cost-Sensitive学习是Cost-Sensitive学习中一个新的课题,这个新课题的目标是使分类过程中的误分类代价、检查代价及分类延时代价之和达到最小。给出包含一种简单的分类延时代价的Cost-Sensitive学习,提出一个既"摊薄"延时代价又减少浪费检查代价的检查策略。 展开更多
关键词 cost—Sensitive学习 分类延时代价 序列检查策略 批检查策略
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Multiple Objective Test Design for Accelerated Destructive Degradation Tests
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作者 黄硕 杨军 +1 位作者 彭锐 赵宇 《Journal of Donghua University(English Edition)》 EI CAS 2015年第6期954-956,共3页
Accelerated destructive degradation tests(ADDTs)are powerful to provide reliability information in the degradation processes with destructive measurements.In order to carry out an ADDT efficiently,both the estimation ... Accelerated destructive degradation tests(ADDTs)are powerful to provide reliability information in the degradation processes with destructive measurements.In order to carry out an ADDT efficiently,both the estimation precision of parameters and the test cost should be considered.On the basis of the given degradation model and failure criterion,a multiple-objective optimization model for the design of ADDTs is proposed.Under constrains of the maximum measurement time,the total sample size and the number of stress levels,a comprehensive target function is suggested to reflect both the precision of lifetime estimation and total cost,and the optimal test plan is obtained,which is composed by optimal choices for samples size,measurement frequency,and the number of measurements at each stress level.A real example is illustrated to demonstrate the implementation of the proposed approach. 展开更多
关键词 accelerated destructive degradation tests(ADDTs) highly reliable products multiple objectives test cost asymptotic variance
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Multiplex Rapid Test with Acceptable Diagnosis Performance as a Solution to Increase Diagnosis of Hepatitis B and C Viruses in Pregnant Women in an Area of High Prevalence of Both Hepatitis Viruses Associated with HIV
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作者 Catherine Boni-Cisse Nina Esther Onstira Ngoyi +9 位作者 Hermione Dahlia Mossoro-Kpinde Noella Packo Rabi Senekian Hermann Ndoidet Koutou Coretha Bokia-Baguida Christelle Luce Bobossi-Gadia Arthur Simplice Sombot-Ndicky Daniel Yvon Gonessa Freddy Samuel Ngbonga Konzapa Voulou Christian Diamant Mossoro-Kpinde 《Open Journal of Medical Microbiology》 2024年第1期50-65,共16页
Background and Objective: HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) are very widespread in the world, however, less than 20% of the people affected are diagnosed and treated. This study aimed to determi... Background and Objective: HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) are very widespread in the world, however, less than 20% of the people affected are diagnosed and treated. This study aimed to determine the prevalence of HIV, HCV and HBV co-infections in pregnant women at Bangui Community University Hospital and the cost of screening. Methods: A cross-sectional study involving consenting pregnant women who came for antenatal care was performed. HIV, HCV antibodies and HBV antigens were detected using Exacto Triplex<sup>?</sup> HIV/HCV/HBsAg rapid test, cross-validated by ELISA tests. Sociodemographic and professional data, the modes of transmission and prevention of HIV and both hepatitis viruses were collected in a standard sheet and analyzed using the Epi-Info software version 7. Results: Pregnant women aged 15 to 24 were the most affected (45.3%);high school girls (46.0%), and pregnant women living in cohabitation (65.3%) were the most represented. Twenty-five (16.7%) worked in the formal sector, 12.7% were unemployed housewives and the remainder in the informal sector. The prevalence of HIV, HBV, and HCV viruses was 11.8%, 21.9% and 22.2%, respectively. The prevalence of co-infections was 8.6% for HIV-HBV, 10.2% for HIV-HCV, 14.7% for HBV-HCV and 6.5% for HIV-HBV-HCV. All positive results and 10% of negative results by the rapid test were confirmed by ELISA tests. The serology of the three viruses costs 39,000 FCFA (60 Euros) by ELISA compared to 10,000 FCFA (15.00 Euros) with Exacto Triplex<sup>?</sup> HIV/HCV/AgHBs (BioSynex, Strasbourg, France). Conclusion: The low level of education and awareness of hepatitis are barriers to development and indicate the importance of improving the literacy rate of women in the Central African Republic (CAR). Likewise, the high prevalence of the three viruses shows the need for the urgent establishment of a national program to combat viral hepatitis in the CAR. 展开更多
关键词 HIV-HCV-HBV Co-Infection Multiplex Immunochromatographic Rapid test Central Africa Serology test cost Diagnostic Accessibility
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多角度协同分析优化分段空场嗣后充填体强度
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作者 彭跃金 《中国矿山工程》 2026年第1期66-73,共8页
为解决分段空场嗣后充填采矿中充填体强度与安全性、经济性及充填料浆流动性的协同优化问题,以某铜矿为研究对象,通过多角度协同分析确定合理充填体强度。结果分析表明,当安全系数取1时,充填体最小强度为1.15~1.24 MPa;安全系数取2时,... 为解决分段空场嗣后充填采矿中充填体强度与安全性、经济性及充填料浆流动性的协同优化问题,以某铜矿为研究对象,通过多角度协同分析确定合理充填体强度。结果分析表明,当安全系数取1时,充填体最小强度为1.15~1.24 MPa;安全系数取2时,最小强度为2.23~2.31 MPa。同时将5种理论计算方法的结果划分为安全冗余区、均衡基准区、结构敏感区。基于能量分析与理论计算,初步选取0.80 MPa、1.60 MPa、2.40 MPa三种充填体强度方案。塌落度试验显示,随强度由0.80 MPa提高到2.40 MPa,料浆塌落度降低20.24%,但仍满足工业泵送要求;对应充填成本则线性上升86.27%。最后进行数值模拟验证结果表明,与0.80 MPa的充填体相比,1.60 MPa的充填体顶板最大竖向位移降低53.24%。继续提高至2.40 MPa时,位移再降69.91%,但成本提高48.34%。综合安全、流动性及经济性,推荐充填体最低强度为1.60 MPa,并在满足可行性与经济性的前提下适度上调。 展开更多
关键词 分段空场嗣后充填 胶结充填体 强度设计 流动性测试 成本分析
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配方施肥对小麦产量、肥料利用率及经济效益的影响
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作者 韦世宏 裴欢 王家嘉 《安徽农学通报》 2026年第1期5-8,共4页
为进一步推广小麦测土配方施肥技术,提高肥料利用率,研究以扬辐麦4号为试验材料,选择2种不同比例的配方肥(配方施肥1,N∶P_(2)O_(5)∶K_(2)O为12.9∶4.7∶5.5;配方施肥2,N∶P_(2)O_(5)∶K_(2)O为12.5∶5.0∶6.5),于2023年10月至2024年6... 为进一步推广小麦测土配方施肥技术,提高肥料利用率,研究以扬辐麦4号为试验材料,选择2种不同比例的配方肥(配方施肥1,N∶P_(2)O_(5)∶K_(2)O为12.9∶4.7∶5.5;配方施肥2,N∶P_(2)O_(5)∶K_(2)O为12.5∶5.0∶6.5),于2023年10月至2024年6月,在安徽省肥西县丰乐镇开展田间肥料利用率试验,每组配方肥均设空白、无氮、无磷、无钾和配方施肥5个处理,测定不同施肥处理对小麦产量及产量构成因素、肥料利用率及经济效益的影响。结果表明,配方施肥对小麦的有效穗数、每穗粒数、千粒重及实际产量均有促进作用,配方施肥1处理和配方施肥2处理的产量分别为6232.5、6147.6 kg/hm^(2);配方施肥1和配方施肥2处理区的氮、磷、钾肥利用率分别为44.7%、25.9%、72.0%和49.1%、22.1%、66.6%;配方施肥1处理和配方施肥2处理的产投比分别为1.96、1.89。综上,测土配方施肥能提高小麦产量、肥料利用率及产投比,在研究区种植小麦时,推荐施用配方肥N∶P_(2)O_(5)∶K_(2)O为12.9∶4.7∶5.5。 展开更多
关键词 小麦 测土配方施肥 肥料利用率 产投比
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通刮捞洗一体化管柱在四川盆地超深井的应用
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作者 谭羲韦 曾宪举 +2 位作者 王欣 李厚杰 杨嘉旭 《天然气技术与经济》 2026年第1期30-36,共7页
为了解决四川盆地超深井试油作业中传统分阶段井筒清洁工艺周期长、成本高、作业风险大,并且井筒结垢与铁屑堆积导致试油管柱下入失败率高的技术难题,同时突破现有一体化清洁工具难以适配超深井高温高压工况的局限,以通刮捞洗一体化管... 为了解决四川盆地超深井试油作业中传统分阶段井筒清洁工艺周期长、成本高、作业风险大,并且井筒结垢与铁屑堆积导致试油管柱下入失败率高的技术难题,同时突破现有一体化清洁工具难以适配超深井高温高压工况的局限,以通刮捞洗一体化管柱为研究对象,在该盆地超深井PS17井开展现场应用验证,分析了该管柱的核心技术原理、结构组成及作业参数优化方法。研究结果表明:①该管柱通过集成通井规、HRC60硬度耐磨合金锯齿形刮削刀具、5000高斯钕铁硼强磁打捞器,结合流体力学计算与斯托克斯定律修正不规则铁屑沉降速度,实现了一趟钻完成通井、刮管、打捞、洗井全流程作业,单井作业时间从传统7~10 d缩短至3 d,井筒垢物清除率达96%,成功打捞8 mm以上片状铁屑4.35 kg,打捞效率较传统一体化工具提升40%;②技术可适配井温介于0~220℃、压力介于0~150 MPa的超深井工况,通过更换通井规与刮削刀具可满足四川盆地主流套管尺寸需求,单井节约成本15~20万元,管柱下入成功率从82%提升至99.5%。结论认为:①通刮捞洗一体化管柱通过功能集成与参数优化,破解了四川盆地超深井井筒清洁的技术瓶颈,其作业高效性、工况适配性与安全可靠性显著优于传统工艺;②该技术兼具经济性与推广价值,可广泛应用于川渝、塔里木等复杂油气田的超深井井筒清洁作业,可以为我国深部油气资源高效开发提供技术支撑。 展开更多
关键词 通刮捞洗一体化管柱 井筒清洁 超深井 流体力学计算 强磁打捞 试油作业 四川盆地 成本优化
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Parallel Test Tasks Scheduling and Resources Configuration Based on GA-ACA 被引量:3
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作者 方甲永 薛辉辉 肖明清 《Journal of Measurement Science and Instrumentation》 CAS 2011年第4期321-326,共6页
A Genetic Algorithm-Ant Colony Algorithm(GA-ACA),which can be used to optimize multi-Unit Under Test(UUT)parallel test tasks sequences and resources configuration quickly and accurately,is proposed in the paper.With t... A Genetic Algorithm-Ant Colony Algorithm(GA-ACA),which can be used to optimize multi-Unit Under Test(UUT)parallel test tasks sequences and resources configuration quickly and accurately,is proposed in the paper.With the establishment of the mathematic model of multi-UUT parallel test tasks and resources,the condition of multi-UUT resources mergence is analyzed to obtain minimum resource requirement under minimum test time.The definition of cost efficiency is put forward,followed by the design of gene coding and path selection project,which can satisfy multi-UUT parallel test tasks scheduling.At the threshold of the algorithm,GA is adopted to provide initial pheromone for ACA,and then dual-convergence pheromone feedback mode is applied in ACA to avoid local optimization and parameters dependence.The practical application proves that the algorithm has a remarkable effect on solving the problems of multi-UUT parallel test tasks scheduling and resources configuration. 展开更多
关键词 parallel test Genetic Algorithm-Ant Colony Algo-rithm GA-ACA cost efficiency multi-UnitUnder test UUT resources configuration tasks scheduling
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代价敏感的指纹可变哈希布谷鸟过滤器 被引量:1
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作者 李猛 罗文啟 +3 位作者 戴海鹏 王瀚橙 顾荣 陈贵海 《软件学报》 北大核心 2025年第7期3358-3374,共17页
布谷鸟过滤器是一种空间高效的近似成员资格查询数据结构,在网络系统中被广泛应用于网络路由、网络测量和网络缓存等.然而,传统的布谷鸟过滤器设计并未充分考虑在网络系统中,部分或全部查询集合已知的情况,以及这部分查询具有代价的情况... 布谷鸟过滤器是一种空间高效的近似成员资格查询数据结构,在网络系统中被广泛应用于网络路由、网络测量和网络缓存等.然而,传统的布谷鸟过滤器设计并未充分考虑在网络系统中,部分或全部查询集合已知的情况,以及这部分查询具有代价的情况.这导致现有的布谷鸟过滤器在该情况下性能无法达到最优.为此,设计了指纹可变哈希布谷鸟过滤器(VHCF).VHCF提出了指纹可变哈希技术,感知已知的查询集合及其代价,通过为每个哈希桶搜索最优指纹哈希函数,从而大幅降低误判代价.随后,每个哈希桶的最优指纹哈希函数会被独立地记录进入每个哈希桶内的哈希索引单元.此外,提出了一种单哈希的技术用于降低引入指纹可变哈希技术导致的额外计算开销,还对VHCF的操作复杂度和误判率进行了理论分析.最后,实验和理论结果都一致表明,VHCF在保证查询吞吐量相当的情况下,取得了比现有布谷鸟过滤器及其变种都要低的误判率.特别的,在保持指纹长度相同的情况下,VHCF只需为每个哈希索引单元分配1–2比特,即可相比标准布谷鸟过滤器降低误判率12.5%–50%. 展开更多
关键词 布谷鸟过滤器 代价敏感 集合成员查询 误判率
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数字贸易发展水平对制造业出口技术复杂度的影响 被引量:1
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作者 孟静 张奥丽 《重庆交通大学学报(社会科学版)》 2025年第1期81-92,共12页
基于2011—2021年中国制造业省级层面的数据,实证检验数字贸易发展水平影响制造业出口复杂度的总体作用、异质性影响和中介机制。研究表明,数字贸易总体上显著促进制造业出口复杂度提升,这一影响对技术密集型行业最为显著,对资本密集型... 基于2011—2021年中国制造业省级层面的数据,实证检验数字贸易发展水平影响制造业出口复杂度的总体作用、异质性影响和中介机制。研究表明,数字贸易总体上显著促进制造业出口复杂度提升,这一影响对技术密集型行业最为显著,对资本密集型行业不显著,对劳动密集型行业起到抑制作用。区域异质性分析发现,中西部地区的数字贸易对制造业出口复杂度的促进作用大于东部地区。中介效应检验发现,数字贸易通过促进技术创新、降低贸易成本影响制造业出口复杂度提升,且技术创新和贸易成本均发挥部分中介作用。基于研究结论,提出加大数字技术研发投入、加强数字贸易基础设施建设和完善数字贸易相关政策支持的建议。 展开更多
关键词 数字贸易 制造业出口技术复杂度 技术创新 贸易成本 机制检验
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A Modified Replacement Model for Items That Fail Suddenly with Variable Replacement Costs
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作者 Samuel Ugochukwu Enogwe Ben Ifeanyichukwu Oruh Emmanuel John Ekpenyong 《American Journal of Operations Research》 2018年第6期457-473,共17页
Several researches have been done to provide better alternative to the existing replacement models, but the research works did not adequately address the replacement problem for items that fail suddenly. Hence, a modi... Several researches have been done to provide better alternative to the existing replacement models, but the research works did not adequately address the replacement problem for items that fail suddenly. Hence, a modified replacement model for items that fail suddenly has been proposed using the knowledge of probability distribution of failure times as well as that of variable replacement cost. The modified cost functions for implementing both individual and group replacements were derived. The modified cost functions were minimized using the principle of classical optimization in order to find the age at which replacement of items would be appropriate. Conditions under which the individual and group replacement policies should be adopted were derived. Two real data sets on failure time of LED bulbs and their replacement costs were used to validate the theoretical claims of this work. In essence, goodness-of-fit test was used to select appropriate probability distribution of failure times as well as that of replacement costs for data sets I and II respectively. The goodness-of-fit results showed that failure times of LED bulbs follow the Smallest Extreme Value and Laplace distributions for data sets I and II respectively. Similarly, it was observed that individual replacement cost followed the two-parameter Gamma and Largest Extreme Value distributions for data sets I and II respectively. Further, the group replacement cost was found to follow the log-normal and two-parameter Weibull distributions for data sets I and II respectively. Based on the empirical study, we observed that individual replacement policy is better than group replacement policy in terms of cost minimization for both existing model and the proposed model. In view of the results, the proposed replacement policy was recommended over the existing one because it yielded lower replacement costs than the existing replacement model. 展开更多
关键词 PROBABILITY Distribution Failure TIMES VARIABLE REPLACEMENT cost GOODNESS-OF-FIT test Group REPLACEMENT INDIVIDUAL REPLACEMENT
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Low-Cost Stormwater Filtration System to Improve Urban Water Quality: The Case of Addis Ababa, Ethiopia
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作者 Dagnachew Adugna Larissa Larsen +1 位作者 Brook Lemma Geremew Sahilu 《Journal of Water Resource and Protection》 2017年第6期692-705,共14页
Urbanization in developing countries often negatively impacts water re-sources by polluting surface waters. Addis Ababa, Ethiopia, is currently experiencing rapid urbanization accompanied by significant water shortage... Urbanization in developing countries often negatively impacts water re-sources by polluting surface waters. Addis Ababa, Ethiopia, is currently experiencing rapid urbanization accompanied by significant water shortages, unmanaged stormwater, and increasing river water pollution. To supplement the need for non-potable water and address stormwater runoff pollution, we constructed a low cost stormwater filtration system. The filtration system is comprised of a sedimentation area followed by three gravel grain sizes arranged horizontally from coarse to medium to fine filter media. We compared the quality of pretreatment water with post-treatment water by measuring physicochemical parameters, heavy metals and nutrients. We found that the filtration system reduced turbidity by 87%, TSS by 80%, Cu by 87% and Zn by 90%. Further, it positively increased the concentration of DO by 42%. However, the filtration system did not remove nitrates and nitrites. Implementing this system at outfalls in the rapidly expanding condominium housing areas can increase residents’ supply of non-potable water and reduce the amount of polluted stormwater entering nearby streams and rivers. 展开更多
关键词 Low cost STORMWATER FILTRATION Addis Ababa Water Quality Performance test
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