共查询到20条相似文献，搜索用时 398 毫秒
1.
Helem Sabina Sánchez Antonio Visioli Ramon Vilanova 《Journal of The Franklin Institute》2017,354(10):3945-3970
In this paper, we propose tuning rules for one degree-of-freedom proportional-integral-derivative controllers, by considering important aspects such as the trade-off in the performance in the servo and regulation operation modes and the control system robustness by constraining the maximum sensitivity peak. The different conflicting objectives are dealt with by using a multi-objective optimization algorithm to generate the trade-off optimal solutions. In this context, a simple tuning rule is determined by using the Nash solutions as a multi-criteria decision making technique. The Nash criteria is shown to provide convenient trade-off solutions for the controller tuning problem. Illustrative simulation examples show the effectiveness of the method. 相似文献
2.
Xiaowei Jiang Xiangyong Chen Junwei Hu Huaicheng Yan Mingfeng Ge 《Journal of The Franklin Institute》2019,356(6):3353-3367
In this paper, the achievable tracking performance limitations of discrete-time, multi-input multi-output (MIMO) networked control systems (NCSs) are studied. The channel is modeled as an additive white Gaussian noise and signal-to-noise ratio (SNR) limited channel with feedback. Under this framework, the closed relationships among stabilization, tracking performance, and SNR limited are quantitatively revealed. Some new results a.erived according to the allpass factorization and Youla parameterization of two degrees of freedom controller. The results show that the best tracking performance is in connection with the unstable poles, non-minimum phase zeros of the system. It is also demonstrated that the tracking performance will be badly degraded by feedback channel noise and due to the SNR limited. Finally, a simulation example is presented to validate the conclusions. 相似文献
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《Information processing & management》2023,60(2):103205
Personalized recommender systems have been extensively studied in human-centered intelligent systems. Existing recommendation techniques have achieved comparable performance in predictive accuracy; however, the trade-off between recommendation accuracy and diversity poses new challenges, as diversification may lead to accuracy loss, whereas it can solve the over-fitting problem and enhance the user experience. In this study, we propose a heuristic optimization-based recommendation model that jointly optimizes accuracy and diversity performance by obtaining a set of optimized solutions. To establish the best accuracy-diversity balance, a novel trajectory-reinforcement-based bacterial colony optimization algorithm was developed. The improved bacterial colony optimization algorithm was comprehensively evaluated by comparing it with eight popular and state-of-the-art algorithms on ten benchmark testing problems with different degrees of complexity. Furthermore, an optimization-based recommendation model was applied to a real-world recommendation dataset. The results demonstrate that the improved bacterial colony optimization algorithm achieves the best overall performance for benchmark problems in terms of convergence and diversity. In the real-world recommendation task, the proposed approach improved the diversity performance by 1.62% to 8.62% while maintaining superior (1.88% to 40.32%) accuracy performance. Additionally, the proposed personalized recommendation model can provide a set of nondominated solutions instead of a single solution to accommodate the ever-changing preferences of users and service providers. Therefore, this work demonstrates the excellence of an optimization-based recommendation approach for solving the accuracy-diversity trade-off. 相似文献
5.
负载自适应的CoMP调度策略 总被引：1，自引：0，他引：1
研究LTE-A下行CoMP调度技术.针对系统负载差异的场景,说明单一CoMP调度模式的缺陷;同时针对2类CoMP技术,给出相应地提高小区边缘和小区整体吞吐量的调度策略.通过理论分析和系统级仿真验证,研究系统负载对调度策略性能的影响,最后提出一种能自适应于非均衡负载的CoMP调度策略.综合评估表明,CoMP联合传输在低负载下和CoMP协调调度在高负载下均具有较优性能,而优化策略复杂度低,且能适应系统负载变化,可进一步提高系统性能. 相似文献
6.
Sajad Koushkbaghi Jesse B. Hoagg T. Michael Seigler 《Journal of The Franklin Institute》2021,358(6):2964-2986
The results of a human-in-the-loop experiment are used to investigate the control strategies that humans use to interact with nonlinear dynamic systems. Two groups of human subjects interact with a dynamic system and perform a command-following task. The first group interacts with a linear time-invariant (LTI) dynamic system. The second group interacts with a Wiener system, which consists of the same LTI dynamics cascaded with a static output nonlinearity. Both groups exhibit improved performance over the trials, but the average of the linear group’s performance is better on more than three-fourths of the trials. A new nonlinear subsystem identification algorithm is presented and used to identify the feedback and feedforward control strategies used by the subjects in both groups. The identification results for the linear group agree with prior studies suggesting that adaptive feedforward inversion is a primary control strategy used by humans for command-following tasks. The main results of this paper address an open question of whether a similar control strategy is used for nonlinear systems. The identification results for the nonlinear group suggest that those subjects also use adaptive feedforward inversion. However, the static output nonlinearity inhibits the human’s ability to approximate the inverse. 相似文献
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从强调“到哪里学习”转向重视“向谁学习”,从强调大公司的作用转向重视新创企业的力量,是促进产业集群升级的新思路。通过将创业和创新搜寻理论引入产业集群研究,以浙江省新创集群企业为对象,本文实证检验了专业知识搜寻战略对新创集群企业创新绩效的影响。研究发现,新创集群企业采取着竞争广度和深度、合作广度和深度、业外广度和深度等六种专业知识搜寻战略,不同的搜寻战略对企业创新绩效产生了不同的影响,竞争广度与深度、业外深度三种搜寻战略有助于产品创新,竞争广度和合作深度两种搜寻战略有助于市场创新。论文最后简要讨论和总结了相关理论贡献和实践启示。 相似文献
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《Information processing & management》2020,57(6):102352
Intracerebral hemorrhage (ICH) is the most serious type of stroke, which results in a high disability or mortality rate. Therefore, accurate and rapid ICH region segmentation is of great significance for clinical diagnosis and treatment of ICH. In this paper, we focus on deep neural networks to automatically segment ICH regions. Firstly, we propose an encoder-decoder convolutional neural network (ED-Net) architecture to comprehensively utilizing both the low-level and high-level semantic information. Specifically, the encoder is used to extract multi-scale semantic feature information, while the decoder integrates them to form a unified ICH feature representation. Secondly, we introduce a synthetic loss function by paying more attention to the small ICH regions to overcome the data imbalanced problem. Thirdly, to improve the clinical adaptability of the proposed model, we collect 480 patient cases with ICH from four hospitals to construct a multi-center dataset, in which each case contains the first and review CT scans. In particular, CT scans of different patients are diverse, which greatly increases the difficulty of segmentation. Finally, we evaluate ED-Net on the multi-center ICH clinical dataset from different model parameters and different loss functions. We also compare the results of ED-Net with nine state-of-the-art methods in the literature. Both quantitative and visual results have shown that ED-Net outperforms other methods by providing more accurate and stable performance. 相似文献
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Carolina López-Nicolás Ángel L. Meroño-CerdánAuthor vitae 《International Journal of Information Management》2011,31(6):502-509
Our aim is to shed light on the consequences of knowledge management (KM) strategies on firm's innovation and corporate performance. Organisations are not aware of the real implications that KM may have. Based on an empirical study consisted of 310 Spanish organisations and structural equations modelling, results show that both KM strategies (codification and personalisation) impacts on innovation and organisational performance directly and indirectly (through an increase on innovation capability). Also, findings demonstrate a different effect of KM strategies on diverse dimensions of organisational performance. Our conclusions may help academics and managers in designing KM strategic programs in order to achieve higher innovation, effectiveness, efficiency and profitability. 相似文献
10.
《Information processing & management》2023,60(2):103227
Recently, the Transformer model architecture and the pre-trained Transformer-based language models have shown impressive performance when used in solving both natural language understanding and text generation tasks. Nevertheless, there is little research done on using these models for text generation in Arabic. This research aims at leveraging and comparing the performance of different model architectures, including RNN-based and Transformer-based ones, and different pre-trained language models, including mBERT, AraBERT, AraGPT2, and AraT5 for Arabic abstractive summarization. We first built an Arabic summarization dataset of 84,764 high-quality text-summary pairs. To use mBERT and AraBERT in the context of text summarization, we employed a BERT2BERT-based encoder-decoder model where we initialized both the encoder and decoder with the respective model weights. The proposed models have been tested using ROUGE metrics and manual human evaluation. We also compared their performance on out-of-domain data. Our pre-trained Transformer-based models give a large improvement in performance with ～79% less data. We found that AraT5 scores ～3 ROUGE higher than a BERT2BERT-based model that is initialized with AraBERT, indicating that an encoder-decoder pre-trained Transformer is more suitable for summarizing Arabic text. Also, both of these two models perform better than AraGPT2 by a clear margin, which we found to produce summaries with high readability but with relatively lesser quality. On the other hand, we found that both AraT5 and AraGPT2 are better at summarizing out-of-domain text. We released our models and dataset publicly1,.2 相似文献
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许多研究认为,自然保护区的建立会导致或加剧当地居民的贫困,本文的分析表明情况未必皆如此。由于经济价值和非经济价值构成自然资源的潜在总价值,自然资源的各种属性紧密地交织在一起,对资源不同属性的利用存在一个权衡问题,自然保护属于偏向于非经济价值的一种权衡手段。为了实现自然资源价值增值的最大化,自然保护重新界定了国家与当地居民对于地方上国有及集体自然资源的产权关系,既限制了国有资源的经济属性的利用,也限制了当地居民的集体资源的部分属性的利用以及他们对国有自然资源部分经济属性的攫取,从而导致对他们经济福利的损害。然而这种福利损失相对份额很小,而且为了弥补该损失地方政府和保护机构往往采取各类扶持措施以增进其福利,从而有效地降低了自然保护的交易成本。自然保护在逻辑上不能必然地引导当地居民脱贫致富,因此必须超越自然保护层面制定经济发展战略。对国家一级野生保护动物——朱鹳的保护区内的农户调查数据证实了上述推断。 相似文献
12.
《Research Policy》2002,31(1):159-182
This paper discusses the role of contractual and organizational arrangements for the governance of supplier–manufacturer relationships in new product development projects. We present cross-sectional project level data from 50 manufacturer–supplier relations in new product development in the European Major Home Appliance industry using a single dyadic interaction as the unit of analysis, to combine institutional decisions driving the governance of inter-firm relations and their organizational implementation. Our results show that (a) relational outcome depends on the type of joint activities, (b) it can be decomposed into short term (efficiency) and long term (learning) effects, (c) less articulate types of joint development activities increase efficiency, while more articulate joint development activities increase partner’s learning, and (d) inter-organizational structuring decisions are significant explanatory variables to understand relational outcome. Implications for the organization of vertical collaboration in new product development projects are derived focusing on the emerging trade-off between short and long term objectives as a central issue in guiding relational strategies. 相似文献
13.
对我国115家高技术企业的知识资产(技术资产、关系资产、和结构资产)特性与组织学习战略和绩效之间的关系进行实证研究,发现默会性以及组织融合与利用型学习战略显著正相关,而声誉、组织融合以及自由自主特性与探索型学习战略显著正相关。声誉对组织绩效影响显著。默会性通过利用型学习战略对组织整体绩效和新产品绩效起作用。探索型学习战略对组织的整体绩效起显著的正面作用但对新产品绩效不存在显著的影响。 相似文献
14.
Innovation strategy and performance during economic transition: Evidences in Beijing, China 总被引：1，自引：0，他引：1
This paper evaluates the relevance of innovation strategy to various categories of Chinese firms and investigates its relationship with innovation performance during the economic transition of the 1990s. Data from 1244 Chinese firms in Beijing are used to ascertain the relative importance of different innovation objectives, along with the innovation strategies adopted by manufacturing firms. Results show that innovation activities were confined to the domestic sphere and mainly directed at quality improvement. Chinese manufacturing firms which obtained support from the government through the high-tech firm accreditation system generally perform better. They had already started moving away from a reliance on imported technology and equipment, and using indigenous R&D efforts to innovate for the coming market economy. 相似文献
15.
节水型社会:理论及其在西北地区的实践与对策 总被引：10，自引：0，他引：10
西北地区面临水资源严重短缺的危机,建设节水型社会是谋求区域经济社会可持续发展的战略选择。本文从理论上探讨了节水型社会的概念及其特征,系统总结了近几年来甘肃省张掖市建设节水性社会的实践经验和成果,提出了在西北地区建立节水型社会的对策体系,主要包括:建立和完善以流域管理为主体的水资源综合管理体制;建立和完善以水资源市场化配置为核心的节水型社会运行机制;优化区域产业结构,提高水资源利用效率;大力调整农业种植结构,逐步形成节水型农业种植体系;加强工业“三废”治理,逐步建立节水防污型工业体系。 相似文献
16.
环境战略能否驱动环境绩效和经济绩效的双赢直接关系到企业开展环境战略的积极性。为此,本文利用中国四大重污染行业2014—2018年的面板数据,实证检验了环境战略与环境绩效和经济绩效的关系。研究得出：①整体而言,企业实施环境战略能够显著实现环境绩效和经济绩效双赢。②进一步分组研究显示,不同成长阶段、不同市场竞争条件的企业环境战略不同,对其两绩效的调节效应也会存在差异,高成长性企业的环境战略显著正向影响环境绩效但并未带来显著的经济绩效,而低成长性企业的环境战略对环境绩效的影响不显著却能带来明显的经济绩效;市场竞争越激烈,环境战略对环境绩效和经济绩效的促进作用越明显,而弱竞争环境下的环境战略则作用效果比较有限。③从环境战略的实施内容看,企业只有重视长期的环境管理、绿色技术创新和绿色文化建设,而非满足于短期排污达标或规避环境违法,才能实现环境绩效和经济绩效的双赢。④新环保法实施后,企业环境战略对环境绩效的提升作用更加突出,但对经济绩效的影响不升反降。 相似文献
17.
This paper investigates the controller design problem of cyber-physical systems (CPSs) to ensure the reliability and security when actuator faults in physical layers and attacks in cyber layers occur simultaneously. The actuator faults are time-varying, which cover bias fault, outage, loss of effectiveness and stuck. Besides that, some state-dependent cyber attacks are launched in control input commands and system measurement data channels, which may lead state information to the opposite direction. A novel co-design controller scheme is constructed by adopting a new Lyapunov function, Nussbaum-type function, and direct adaptive technique, which may further relax the requirements of actuator/sensor attacks information. It is proven that the states of the closed-loop system asymptotically converge to zero even if actuator faults, actuator attacks and sensor attack are time-varying and co-existing. Finally, simulation results are presented to show the effectiveness of the proposed control method. 相似文献
18.
《The Journal of High Technology Management Research》2001,12(1):139-165
This paper develops four categories of knowledge management strategies used by multinational corporations (MNCs). Codification strategies involve the transformation of tacit knowledge into explicit knowledge in order to facilitate flows of organizational knowledge. Tacitness strategies keep organizational knowledge tacit in order to prevent flows of knowledge to competitors. Focused knowledge management strategies regulate knowledge flows by controlling the degree to which knowledge is encoded in forms that match the information intensity and ambiguity of their knowledge. Unfocused knowledge management strategies attempt to regulate knowledge flows by controlling the overall level of codification of knowledge without special consideration of the capabilities of specific forms of codification. Empirical analyses of the effects of these strategies on subunit performance in a sample of US and Danish subsidiaries suggest that the focused strategies are superior to the other strategies. Our results also indicate that different kinds of organizational knowledge require matching forms of codification in order to increase performance. The results give rise to a nested contingency model of knowledge management. 相似文献
19.
2001 年至2010 年三峡库区重庆段植被活动时空特征及其影响因素 总被引：2，自引：0，他引：2
利用2001年-2010年的MODIS陆地产品MODl3A3NDVI数据对三峡库区重庆段近10年来的植被生长状况及其影响因素进行分析,结果表明：①三峡库区重庆段东部、中南部中高山区NDVI较高,西部川东平行岭谷区,长江干流及其支流谷地NDVI较低;地形和人类建设活动成为主要的影响因素;②近10年来三峡库区重庆段植被活动总体上呈逐渐增强的趋势;③研究区植被活动出现极化的趋势,植被稀疏的区域植被活动进一步减小,植被茂密的区域植被活动保持稳定或增强,夏季最为明显;（D研究区6种植被类型中,阔叶林的NDVI最高,为0．6904;水生植被的NDVI最低,为0．5710。草甸和灌丛、灌草丛两种植被类型增长最为迅速,分别为0．6％和0．48％;⑤地形、坡度和地形起伏度是影响三峡库区重庆段植被生长状况最为重要的因素,三个因素从根本上决定了植被的空间分布与变化轨迹。其中,地形起伏是坡度与地形起伏度形成的充分条件,成为最根本的决定性影响因素,同时,人类活动已经成为该区植被退化的主要因素。 相似文献
20.
In this paper, we investigate the optimal denial-of-service attack scheduling problems in a multi-sensor case over interference channels. Multiple attackers aim to degrade the performance of remote state estimation under attackers’ energy constraints. The attack decision of one attacker may be affected by the others while all attackers find their own optimal strategies to degrade estimation performance. Consequently, the Markov decision process and Markov cooperative game in two different information scenarios are formulated to study the optimal attack strategies for multiple attackers. Because of the complex computations of the high-dimensional Markov decision process (Markov cooperative game) as well as the limited information for attackers, we propose a value iteration adaptive dynamic programming method to approximate the optimal solution. Moreover, the structural properties of the optimal solution are analyzed. In the Markov cooperative game, the optimal joint attack strategy which admits a Nash equilibrium is studied. Several numerical simulations are provided to illustrate the feasibility and effectiveness of the main results. 相似文献