首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
The paper criticizes the currently dominant view of organization forms as “discrete alternatives” and “coherent” set attributes, and proposes a more refined and micro-analytic view of organization forms as particular combinations of coordination mechanisms and rights allocations. This view is relevant for understanding and devising “new” forms and proposing solutions for governing the composite and fast changing systems of today. The view is “relational” as it offers a procedure for devising “superior” configurations as combinations—relations between organizational components—in a quasi-continuous space of possibilities. The approach is sustained by the quantitative methods of network analysis as applied to relations among firm's resources and activities. Theoretically, the approach revisits organization design, integrating classic organization theory tenets with the new inputs provided by organizational economics. Substantively, it is argued that a mix of much differentiated coordination mechanisms is usually superior to the codified, “packaged”, allegedly “coherent”, forms of organization. The procedure presented in the paper is applied to a field experiment in a medium size firm.1  相似文献   

2.
This paper firstly examines the relationship between state coordination and wind energy growth by comparing the differences between UK and German institutional configurations and state involvements in the 1990s. While the EU was calling for a unified regulatory framework for its member states, the UK and Germany adopted very different renewable energy policies. The evidence of the early 1990s shows that the British government employed “deregulation” with so limited state involvement that wind energy project developers faced thorny development problems, while the German government tried to require the electricity supply industry to purchase expensive wind power by “regulation” but encountered formidable resistance. Nevertheless, both the British and German administrations later could resolve these problems through new forms of state power. This suggests that, firstly, neither “deregulation” nor “regulation” is an effective means to develop wind power with increasing electricity liberalization and regionalization. Secondly, “obliging” regulations and state powers are vital to the policy outcome by harnessing the state's institutional capacity to smooth out technology innovation and diffusion.  相似文献   

3.
The deposition rate and the thickness uniformity of chemical vapor deposition (CVD) titanium nitride films depend on wafer temperatures. The heater surface conditions, such as flatness, roughness, and surface imperfections, can greatly affect heat transfer efficiency from the heater surface to the wafer, and the process performance. Because heater surface imperfections or “hot spots” that caused poor uniformity had to be eliminated, the origin of “hot spots” was identified by a detailed study of heater surface profiles. A better visualization of “hot spots” could be obtained by comparing wafer-chucking patterns with deposition patterns. Thus, the time needed to locate “hot spots” could be shortened. The manufacturing process was revised to prevent “hot spots” and improve heater performance.  相似文献   

4.
This article presents an application of the “Six Sigma” DMAIC model to G.E.P. Box's famous “paper helicopter” experiment. The define, measure, and analyze phases are presented here, and the improve and control phases are presented in a follow-up article. The intent of this article is to present the reader with a case study for structuring a “Six Sigma” Black Belt project.  相似文献   

5.
A major challenge in the formulation of optimization models for large-scale, complex operational problems is that some data are impossible or uneconomical to collect, producing a cost model that suffers from incomplete information. As a result, even an optimal solution may be “wrong” in the sense that it is solving the wrong problem. In many operational settings, knowledgeable experts will already know, at least approximately, how a model should behave, and can express this knowledge in the form of low dimensional patterns: “high powered locomotives should pull intermodal trains” (because they need to move quickly) or “loaded C-141s should not be flown into Saudi Arabia” (for maintenance reasons). Unlike the literature on inverse optimization which uses observed actions to train the parameters of a cost model, we used exogenous patterns to guide the behavior of a model using a proximal point term that penalizes deviations from these patterns. Under the assumption that the patterns are derived from rational behaviors, we establish the conditions under which incorporating patterns will reduce actual costs rather than just the engineered costs. The effectiveness of the approach is demonstrated in a controlled, laboratory setting using data from a major railroad.  相似文献   

6.
Computers are increasingly employed to monitor the performance of complex systems. An important issue is how to evaluate the performance of such monitors. In this article we introduce a three-dimensional representation that we call a “waterfall chart” of the probability of an alarm as a function of time and the condition of the system. It combines and shows the conceptual relationship between the cumulative distribution function of the run length and the power function. The value of this tool is illustrated with an application to Page's one-sided Cusum algorithm. However, it can be applied in general for any monitoring system.  相似文献   

7.
In this paper, the principle of a solution for “thermal” connection between two solids is analyzed. We shows results given by the solution applied to the mechanical behaviour of a γ/γ′ two-phase material and to “artificial” structures obtained from modern techniques for epitaxial deposit. It appears that the use of a true or fictitious thermal loading constitutes a simple “connection” procedure, but is particularly coherent with the mechanics of two-phase crystalline materials with different lattice parameters. It would be interesting to apply the model to real structures, with misfit and interfacial dislocations.  相似文献   

8.
The basic properties of glasses and the characteristics of mechanical relaxation in glasses were briefly reviewed, and then our studies concerned were presented. Experimental methods adopted were viscosity, internal friction, ultrasonic attenuation, and Brillouin scattering measurements. The specimens used were several kinds of inorganic, organic, and metallic glasses. The measurements were mainly carried out from the room temperature up to the glass transition temperature, and the relaxation time was determined as a function of temperature. The “double relaxation” composed of two Arrhenius-type relaxations was observed in many materials. In both relaxations, the “compensation effect” showing a correlation of the pre-exponential factor and the activation energy was observed. These results were explained by considering the “complex relaxation” due to cooperative motions of atoms or group of atoms. Values of activation energy near the glass transition determined by the various experimental methods were compared with each other.  相似文献   

9.
The “edge-on” illuminated microchannel plate (MCP) position-sensitive detector (PSD) is used for gamma-ray imaging for the first time. The superior position resolution of the MCP is combined with high detection efficiency due to the “edge-on” illumination mode. The results of imaging a 15 μCi 137Cs source (662 keV quantum energy) are presented.  相似文献   

10.
Energy is an important component of the total productivity question and since its costs have been increasing faster than the rate of inflation, its importance is growing over time. As with most productivity measurement, energy productivity is difficult to monitor due to lack of metering and lack of data on “standard energy costs.” Also, manufacturers differ greatly in their energy use profile due to such variables as location, weather, number of people, product, manufacturing intensity, and a host of others. This paper examines energy productivity monitoring and control measurement systems. Standard “one-shot” efficiency measures are examined and then some unique ideas and more sophisticated computer programs (BLAST and DOE II) for calculating standard energy costs are presented and discussed.  相似文献   

11.
The structure and mechanical properties of new types of non-crystalline metallic composites, namely “glass-quasi-crystal”, “glass-disclinated nanocrystal” and “quasi-crystal(-glass)-disclinated nanocrystal” composites are theoretically examined. In particular, a theoretical model is proposed which effectively describes the relationship between plastic deformation and the growth of the glassy phase in metallic “glass-quasi-crystal” composite materials. Here also basic features of both the structure and the mechanical properties of the “glass-disclinated nanocrystal” and “quasi-crystal(-glass)-disclinated nanocrystal” composites are theoretically examined. It is shown that such composites are characterized by a very high yield stress.  相似文献   

12.
This paper is dedicated to the analysis of the local phenomena which give rise to anisotropy in granular materials. This anisotropy can be observed for small strains (“elastic strains”) as well as large irreversible strains (“plastic strains”). Elastic anisotropy appears to be due to the distribution of contacts, the shape of particles and the non-linear local contact law. Anisotropic non-reversible behaviour seems to be related to two kinds of anisotropy, the usual geometric anisotropy and a static anisotropy governing the distribution of contact forces.  相似文献   

13.
Recent laboratory studies have shown that metal nanoparticles-decorated single-walled carbon nanotubes (SWCNTs) can be used to detect carbon monoxide (CO) gases at room temperature, which is known not able to be adsorbed on pure SWCNTs. In this paper, we investigated the Rh-decorated (8,0) SWCNT and its interaction with CO gases by using density functional theory (DFT) methods. Upon Rh atom adsorption, the conductivity of the (8,0) SWCNT and the atomic charges of some carbon atoms around Rh atom are enhanced dramatically. The Rh-adsorption may be thought of as providing “activated” carbon-sites of adsorbing foreign species. Both the Rh-site and the “activated” C-sites are considered as reactivity sites for the adsorption of CO gases. The binding energy is larger for CO-adsorption on the Rh-site than on the “activated” C-sites. Since the interaction between CO gases and the Rh-site is very strong, the Rh-decorated SWCNT is not reusable for CO gases detecting due to the large binding energy. On the other hand, the CO gases can also be adsorbed on the “activated” C-site with the binding energy of about −0.80 eV and 0.12 electrons transfer. The electronic properties have changed dramatically upon the CO gases. These calculation results are useful not only to explain the sensing mechanisms but also to evaluate the potential for SWCNTs-based sensing materials at room temperature.  相似文献   

14.
The problem of the debonding of an elastic layer from the wall of a uniformly contracting cavity is considered for the case where a segment of the layer is initially delarmnated and is predeflected due to the presence of a “knife edge imperfection” on the surface of the substrate or equivalently by a point load applied to the layer. A closed form analytical solution is obtained and numerical results are presented demonstrating the influence of the “imperfection” on the phenomenon of interest.  相似文献   

15.
Electronic conductance switching in devices based on thin films of an organic molecule has been studied. Switching between two conducting states has been induced by voltage pulse, while the states have been probed by optical and electrical measurements simultaneously. In situ optical measurements showed that electroreduction of molecules led to conductance switching and appearance of high-conducting state in the device. We could “write” or “erase” a state by applying electrical pulse and “read” it by measuring electronic absorbance and conductivity. The “write” and “read” processes have been carried out for many cycles to exhibit a correspondence between conductance switching and electrochromism.  相似文献   

16.
The possible effect of proposed cyclic fluctuations of human sensitivity (28 days), intelligence (33 days), and physical (23 days) characteristics on motor vehicle accidents and fatalities was examined. Three methods of calculating these theoretical cycles were also examined. One method, the “Biomate” computer, was found to be unreliable in that it indicated 10.6% more days designated by the theory as critical than were actually present in a 300 case sample. In a sample of 141 motor vehicle fatalities (64 drug-free and 77 drug-associated) no correlation with the theoretical critical days was found for either group beyond that expected from random distribution. No evidence was found to support the increased likelihood of accident involvement on the “critical day” as implied by the concept of the “biorhythm” theory. Several possible sources of error in previously published reports are discussed.  相似文献   

17.
Scheduling outpatients and medical operation rooms has the following structure: Nusers are given appointment times to use a facility, the duration required by the facility to service each user is stochastic. The system incurs a “user idle cost” if a user arriving at the appointed time finds the facility still engaged by preceding users, while a “facility idle cost” is incurred if the facility becomes free before the next user arrives. We develop an accurate procedure to compute the expected total system costs for any given appointment schedule. Compared to earlier related procedures, ours is much faster and can handle larger problems as well as very general service-time distributions. We then show that this fast computation procedure enables one to determine easily the “lowest-cost appointment schedule” for any given “job” (i.e., “user”) sequence. This in turn will enable one to search for the optimal job sequence that has the best “lowest-cost appointment schedule”.  相似文献   

18.
A CopleyTM fraction collector and a DisotestTM flow-through system were coupled to provide an automatic discrete sampling flow-through dissolution system for use both in the “open-loop” and “closed-loop” mode. The system was used to investigate the release characteristics of adinazolam in sustained release formulations using a pH 1.2 simulated gastric fluid (without enzymes) dissolution medium (USP XXI). These experimental formulations are designed to provide relatively slow to rapid drug release. The dissolution effluent was analysed off-line by reverse phase HPLC to determine the adinazolam concentration at programmed timed intervals. The differential dissolution profiles produced when the system is used in the “open-loop” configuration are more discriminating in describing the release characteristics of the formulations according to the relative release rates than the “closed-loop” cumulative profiles. Using the characteristic dissolution time parameter from the Weibull function, a better correlation with in vivo bioavailability data was achieved for the data from the system in the “open-loop” mode than when it was used in the “closed-loop” mode. In the “open-loop” mode the Weibull function characteristic dissolution time parameter yielded the best quantitative correlation with a correlation coefficient of 0.92 compared to a value of 0.85 for the “closed-loop” configuration  相似文献   

19.
Various “living” polymers were grafted onto C60 The number of arms of the so obtained “star” molecules can be controlled by stoechiometry and/or by varying the reactivity of the carbanion on the “living” chain against a double bond on the C60. Even the oxanion of “living” polyethylenoxide is able to add onto the reactive double bonds on C60. In some conditions, the carbanions present on these alkaline salts of grafted fullerenes becomes able to initiate anionic polymerization of vinyl monomers. Using “living” poly(phenylvinylsulfoxide) as a precursor polymer for PA, polyacetylene chains could be attached to the fullerene.  相似文献   

20.
An analysis of the dispersion of elastic waves is presented for two types of long ultrasonics wave-guides that we qualify of “bimorph”: (i) a “three-layer” guide made of two different materials and (ii) a “clad core” guide built up of a rectangular core surrounded by a cladding, the materials of the rod and cladding having different properties. An analytical model is proposed to describe the extensional, flexural and torsional motions in “bimorph” wave guides having two geometrical and material symmetry axes. The asymptotic behaviour of the model allows one to select the material properties which lead to modes guided essentially either in the central layer or in the core of the bimorph guide. Moreover, the dispersive properties of a “bimorph” can be controlled through the choice of geometrical and material parameters.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号