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141.
从“十四五”保护与发展的生态关系角度,探讨了生态保护与绿色发展的十大生态关系,阐述了生态保护和绿色发展中的一系列有关生态关系的生态智慧及生态技术,并对长江、黄河等流域的生态保护和修复提出了相关建议。 相似文献
142.
FROM MANUFACTURING SCHEDULING TO SUPPLY CHAIN COORDINATION:THE CONTROL OF COMPLEXITY AND UNCERTAINTY
Peter B.LUH 《系统科学与系统工程学报(英文版)》2003,12(3):279-297
With time-based competition and rapid technology advancements, effective manufacturingscheduling and supply chain coordination are critical to quickly respond to changing marketconditions. These problems, however, are difficult in view of inherent complexity and variousuncertainties involved. Based on a series of results by the authors, decomposition and coordination byusing Lagrangian relaxation is identified in this paper as an effective way to control complexity anduncertainty.A manufacturing scheduling problem is first formulated within the job shop context withuncertain order arrivals, processing times, due dates, and part priorities as a separable optimizationproblem. A solution methodology that combines Lagrangian relaxation, stochastic dynamicprogramming, and heuristics is developed. Method improvements to effectively solve large problemsare also highlighted. To extend manufacturing scheduling within a factory to coordinate autonomicmembers across chains of suppliers, a decentralized supply chai 相似文献
143.
This paper analyzes a discrete-time multiple vacations finite-buffer queueing system with batch renewal input in which inter-arrival time of batches are arbitrarily distributed.Service and vacation times are mutually independent and geometrically distributed.The server takes vacations when the system does not have any waiting jobs at a service completion epoch or a vacation completion epoch.The system is analyzed under the assumptions of late arrival system with delayed access and early arrival system.Using the supplementary variable and the imbedded Markov chain techniques, the authors obtain the queue-length distributions at pre-arrival,arbitrary and outside observer’s observation epochs for partial-batch rejection policy.The blocking probability of the first-,an arbitrary-and the last-job in a batch have been discussed.The analysis of actual waiting-time distributions measured in slots of the first-,an arbitrary- and the last-job in an accepted batch,and other performance measures along with some numerical results have also been investigated. 相似文献
144.
Richard B. Watson 《Systemic Practice and Action Research》2012,25(5):441-456
Soft systems methodology (SSM) is now 40?years old. Another decade has passed since Checkland??s thirty year retrospective on the methodology, published in 2000. It can now be described as an old methodology. But it has adapted and changed over the years and is still very much alive, although the days are long gone when it was mainly developed and practised by its founders at the University of Lancaster. Interestingly, considering that many applications of SSM over the years have been to information systems, it was developed before the age of personal computers and the Internet. The way SSM is viewed has changed over the years as it has been applied to various types of problem situation. Every use of SSM will potentially hold methodological lessons in addition to those about the situation of concern; these may include SSMs framework of ideas, processes and way of use. How is SSM going to change in the future? This will depend in part on the types of problem situation to which it is applied. This paper examines some problem situations associated with emerging technologies in the information age to which SSM has not yet been much applied. These include computer simulation and virtual reality, ubiquitous computing and the design of cities, Information Technology Service Management and the design of enterprise information architectures. Some of the different worldviews associated with these problem situations which could be explored using SSM are noted. 相似文献
145.
<正> In this paper,an equivalency condition of nonsingularity in nonlinear semidefinite programming,which can be viewed as a generalization of the equivalency condition of nonsingularity for linearsemidefinite programming,is established under certain conditions of convexity. 相似文献
146.
Alexey B. Petrovsky 《系统科学与系统工程学报(英文版)》2007,16(1):22-33
There are many practical decision problems where decision makers' preferences may be inconsistent and contradictory. In this paper, new methods for ordering and classifying multi-attribute objects by discordant collective preferences are suggested. These methods are based on the theory of multiset metric spaces. The proposed techniques are applied to ranking companies and a competitive selection of projects, which are estimated by several experts upon multiple qualitative criteria. 相似文献
147.
The purpose of the paper is to present a framework that enables action researchers to create quality action research projects within the organization development (OD) domain using the broad criteria of being rigorous, reflective and relevant and so contribute to the realm of practical knowing. What constitutes good quality action research within OD is a difficult question, given the broad range of approaches that operates in a wide variety of settings and with great diversity. It advances specific dimensions by which action researchers can create, review and assess quality in action research work. This integrative framework and criteria are practical tools to enable action researchers to create quality action research in OD. 相似文献
148.
van Kasteren SI Kramer HB Jensen HH Campbell SJ Kirkpatrick J Oldham NJ Anthony DC Davis BG 《Nature》2007,446(7139):1105-1109
One of the most important current scientific paradoxes is the economy with which nature uses genes. In all higher animals studied, we have found many fewer genes than we would have previously expected. The functional outputs of the eventual products of genes seem to be far more complex than the more restricted blueprint. In higher organisms, the functions of many proteins are modulated by post-translational modifications (PTMs). These alterations of amino-acid side chains lead to higher structural and functional protein diversity and are, therefore, a leading contender for an explanation for this seeming incongruity. Natural protein production methods typically produce PTM mixtures within which function is difficult to dissect or control. Until now it has not been possible to access pure mimics of complex PTMs. Here we report a chemical tagging approach that enables the attachment of multiple modifications to bacterially expressed (bare) protein scaffolds: this approach allows reconstitution of functionally effective mimics of higher organism PTMs. By attaching appropriate modifications at suitable distances in the widely-used LacZ reporter enzyme scaffold, we created protein probes that included sensitive systems for detection of mammalian brain inflammation and disease. Through target synthesis of the desired modification, chemistry provides a structural precision and an ability to retool with a chosen PTM in a manner not available to other approaches. In this way, combining chemical control of PTM with readily available protein scaffolds provides a systematic platform for creating probes of protein-PTM interactions. We therefore anticipate that this ability to build model systems will allow some of this gene product complexity to be dissected, with the aim of eventually being able to completely duplicate the patterns of a particular protein's PTMs from an in vivo assay into an in vitro system. 相似文献
149.
Baumann T Amthor AM Bazin D Brown BA Folden CM Gade A Ginter TN Hausmann M Matos M Morrissey DJ Portillo M Schiller A Sherrill BM Stolz A Tarasov OB Thoennessen M 《Nature》2007,449(7165):1022-1024
A fundamental question in nuclear physics is what combinations of neutrons and protons can make up a nucleus. Many hundreds of exotic neutron-rich isotopes have never been observed; the limit of how many neutrons a given number of protons can bind is unknown for all but the lightest elements, owing to the delicate interplay between single particle and collective quantum effects in the nucleus. This limit, known as the neutron drip line, provides a benchmark for models of the atomic nucleus. Here we report a significant advance in the determination of this limit: the discovery of two new neutron-rich isotopes--40Mg and 42Al--that are predicted to be drip-line nuclei. In the past, several attempts to observe 40Mg were unsuccessful; moreover, the observation of 42Al provides an experimental indication that the neutron drip line may be located further towards heavier isotopes in this mass region than is currently believed. In stable nuclei, attractive pairing forces enhance the stability of isotopes with even numbers of protons and neutrons. In contrast, the present work shows that nuclei at the drip line gain stability from an unpaired proton, which narrows the shell gaps and provides the opportunity to bind many more neutrons. 相似文献
150.
Piccioni G Drossart P Sanchez-Lavega A Hueso R Taylor FW Wilson CF Grassi D Zasova L Moriconi M Adriani A Lebonnois S Coradini A Bézard B Angrilli F Arnold G Baines KH Bellucci G Benkhoff J Bibring JP Blanco A Blecka MI Carlson RW Di Lellis A Encrenaz T Erard S Fonti S Formisano V Fouchet T Garcia R Haus R Helbert J Ignatiev NI Irwin PG Langevin Y Lopez-Valverde MA Luz D Marinangeli L Orofino V Rodin AV Roos-Serote MC Saggin B Stam DM Titov D Visconti G 《Nature》2007,450(7170):637-640
Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright 'dipole' feature surrounded by a cold 'collar' at its north pole. The polar dipole is a 'double-eye' feature at the centre of a vast vortex that rotates around the pole, and is possibly associated with rapid downwelling. The polar cold collar is a wide, shallow river of cold air that circulates around the polar vortex. One outstanding question has been whether the global circulation was symmetric, such that a dipole feature existed at the south pole. Here we report observations of Venus' south-polar region, where we have seen clouds with morphology much like those around the north pole, but rotating somewhat faster than the northern dipole. The vortex may extend down to the lower cloud layers that lie at about 50 km height and perhaps deeper. The spectroscopic properties of the clouds around the south pole are compatible with a sulphuric acid composition. 相似文献