Optimal Perturbations in the Eady Model: Resonance versus PV Unshielding

2005 ◽  
Vol 62 (2) ◽  
pp. 492-505 ◽  
Author(s):  
H. de Vries ◽  
J. D. Opsteegh
Keyword(s):  
Growth Mechanism ◽  
Dominant Role ◽  
Resonance Effect ◽  
Potential Temperature ◽  
Region Of Interest ◽  
Building Blocks ◽  
Edge Wave ◽  
Initial Surface ◽  
Optimal Perturbation ◽  
Resonant Level

Abstract Using a nonmodal decomposition technique based on the potential vorticity (PV) perspective, the optimal perturbation or singular vector (SV) of the Eady model without upper rigid lid is studied for a kinetic energy norm. Special emphasis is put on the role of the continuum modes (CMs) in the structure of the SV, and on the importance of resonance to the SV evolution. The basis for the SV is formed by a number of nonmodal structures, each consisting of a superposition of one CM and one edge wave, such that the initial surface potential temperature (PT) is zero. These nonmodal structures are used as PV building blocks to construct the SV. The motivation for using a nonmodal approach is that no attempt has been made so far to include the CM residing at the steering level of the surface edge wave in the perturbation, although it is known that this CM is in linear resonance with the surface edge wave. Experiments with one PV building block in the initial disturbance show that the SV growth is dominated by the resonance effect except for small optimization times (less than 1 day), in which case the unshielding of PV and surface PT dominates the growth of the SV. The PV–PT unshielding provides additional growth to the SV and this explains the observation that the PV resides above the resonant level. More PV building blocks are added to include PV unshielding as a third growth mechanism. Which of the three mechanisms dominates during the SV evolution depends on the region of interest (interior or surface), as well as on the optimization time and on the number of building blocks used. At the surface, resonance plays a dominant role even when a large number of building blocks is used and relatively small optimization times are used. For the interior of the domain, PV unshielding becomes the dominant growth mechanism when more than two PV building blocks are used. With increasing optimization times, the PV distribution of the SV becomes increasingly more concentrated near the steering level of the edge wave. This concentration of PV is explained by the enhanced importance of resonance for long optimization times as compared to short optimization times.

scholarly journals Resonance in Optimal Perturbation Evolution. Part I: Two-Layer Eady Model

2007 ◽  
Vol 64 (3) ◽  
pp. 673-694 ◽  
Author(s):  
H. de Vries ◽  
J. D. Opsteegh
Keyword(s):  
Normal Mode ◽  
Potential Vorticity ◽  
Resonance Effect ◽  
Baroclinic Instability ◽  
Building Blocks ◽  
Variable Number ◽  
Optimal Perturbation ◽  
Surface Development ◽  
Time Optimal ◽  
Asymptotic Normal

Abstract A detailed investigation has been performed of the role of the different growth mechanisms (resonance, potential vorticity unshielding, and normal-mode baroclinic instability) in the evolution of optimal perturbations constructed for a two-layer Eady model and a kinetic energy norm. The two-layer Eady model is obtained by replacing the conventional upper rigid lid by a simple but realistic stratosphere. To make an unambiguous discussion possible, generally applicable techniques have been developed. At the heart of these techniques lies a description of the linear dynamics in terms of a variable number of potential vorticity building blocks (PVBs), which are zonally wavelike, vertically localized sheets of potential vorticity. If the optimal perturbation is composed of only one PVB, the rapid surface cyclogenesis can be attributed to the growth of the surface PVB (the edge wave), which is excited by the tropospheric PVB via a linear resonance effect. If the optimal perturbation is constructed using multiple PVBs, this simple picture is modified only in the sense that PV unshielding dominates the surface amplification for a short time after initialization. The unshielding mechanism rapidly creates large streamfunction values at the surface, as a result of which the resonance effect is much stronger. A similar resonance effect between the tropospheric PVBs and the tropopause PVB acts negatively on the surface streamfunction amplification. The influence of the stratosphere to the surface development is negligible. In all cases reported here, the growth due to traditional normal-mode baroclinic instability contributes either negative or only little to the surface development up to the optimization time of two days. It takes at least four days for the flow to become fully dominated by normal-mode growth, thereby confirming that finite-time optimal perturbation growth differs in many aspects fundamentally from asymptotic normal-mode baroclinic instability.

scholarly journals Resonance in Optimal Perturbation Evolution. Part II: Effects of a Nonzero Mean PV Gradient

2007 ◽  
Vol 64 (3) ◽  
pp. 695-710 ◽  
Author(s):  
H. de Vries ◽  
J. D. Opsteegh
Keyword(s):  
Potential Vorticity ◽  
Propagation Speed ◽  
Building Blocks ◽  
Joint Effect ◽  
Optimal Perturbation ◽  
Orr Mechanism ◽  
Nonzero Mean ◽  
Low Levels ◽  
Pv Gradient

Abstract Optimal perturbations are constructed for a two-layer β-plane extension of the Eady model. The surface and interior dynamics is interpreted using the concept of potential vorticity building blocks (PVBs), which are zonally wavelike, vertically confined sheets of quasigeostrophic potential vorticity. The results are compared with the Charney model and with the two-layer Eady model without β. The authors focus particularly on the role of the different growth mechanisms in the optimal perturbation evolution. The optimal perturbations are constructed allowing only one PVB, three PVBs, and finally a discrete equivalent of a continuum of PVBs to be present initially. On the f plane only the PVB at the surface and at the tropopause can be amplified. In the presence of β, however, PVBs influence each other’s growth and propagation at all levels. Compared to the two-layer f-plane model, the inclusion of β slightly reduces the surface growth and propagation speed of all optimal perturbations. Responsible for the reduction are the interior PVBs, which are excited by the initial PVB after initialization. Their joint effect is almost as strong as the effect from the excited tropopause PVB, which is also negative at the surface. If the optimal perturbation is composed of more than one PVB, the Orr mechanism dominates the initial amplification in the entire troposphere. At low levels, the interaction between the surface PVB and the interior tropospheric PVBs (in particular those near the critical level) takes over after about half a day, whereas the interaction between the tropopause PVB and the interior PVBs is responsible for the main amplification in the upper troposphere. In all cases in which more than one PVB is used, the growing normal mode configuration is not reached at optimization time.

Metallic Nanowires From Carbon Nanotube Building Blocks: The Effect of Atomic Defects on the Nanotube Influencing Nanowire Growth

2003 ◽  
Author(s):  
B. Panchapakesan ◽  
Kousik Sivakumar ◽  
Shaoxin Lu
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Electric Field ◽  
Building Blocks ◽  
Model Systems ◽  
Initial Surface ◽  
Sensors And Actuators ◽  
Platinum Nanowires ◽  
Defect Sites ◽  
Current Densities

Manipulation and control of matter at the nano- and atomic level are crucial for the success of nano-scale sensors and actuators. The ability to control and synthesize multilayer structures using carbon nanotubes that will enable to build electronic devices within a nanotube is still in its infancy. In this paper, we present results on selective electric field assisted deposition of metals on carbon nanotubes realizing metallic nanowire structures. Silver and platinum nanowires has been fabricated using this approach due to its applications in chemical sensing sensing as catalytic materials to sniff toxic agents and in the area of biomedical nanotechnology for construction of artificial muscles. The electric field assisted technique allows the deposition of metals with high degree of selectivity on carbon nanotubes by manipulating the charges on the surface of the nanotubes. The thickness and the growth of the nanowires was altered by inducing defects on the initial surface of the nanotubes that affected the local current densities and electrochemical reduction of silver and platinum on those defect sites. SEM and TEM investigations revealed silver and platinum nanowires between 10 nm-100 nm in diameter. Relatively higher metal deposition was achieved in defect related sites or places where the nanotubes criss-crossed each other, due to the high current densities in these sites. The present technique is versatile and enables the fabrication of host of different types of metallic and semiconduting nanowires using carbon nanotube templates for nanoelectronics and myriad of sensor applications. Further, nanowires can also serve as model systems for studying quantum size effects in these dimensions.

Experimental and theoretical studies of the mica polymorphs

1956 ◽  
Vol 31 (234) ◽  
pp. 209-235 ◽  
Author(s):  
J. V. Smith ◽  
H. S. Yoder
Keyword(s):  
Growth Mechanism ◽  
Theoretical Study ◽  
Dominant Role ◽  
Spiral Growth ◽  
Theoretical Studies ◽  
X Ray ◽  
Layer Cell ◽  
Triclinic Structure ◽  
Experimental And Theoretical Studies ◽  
Made In

SummaryAn experimental and theoretical study has been made in order to determine the number and the structure of the possible polymorphs and to determine the structural relations between them. The simplest structures are 1M, 2M1, 2M2, 3T, 20, and 6H polymorphs, and more complicated types can be developed. Some of the previously described polymorphs were not contained in the theoretical list and were re-examined. The 6M structure was found to be a 2M2 polymorph, the 6-layer triclinic type was found to be a 2M1 polymorph, and the 3M structure was shown to be a 3T type. The 24-layer triclinic structure could be described on a simpler 8-layer cell. This type together with a new 12-layer monoclinic structure, as well as other structures of higher periodicity, presumably consists of complex stacking and results from spiral-growth mechanism. Two extreme types of layer-disordered crystals may be built and a disorder of individual ions may also occur. Single stacking faults result in twinned crystals. A new twin relation (180° rotation about the [100] axis) has been recognized. Twenty specimens from extreme geological environments have been examined in order to evaluate the control of environment on the stacking. The type of stacking could not be attributed solely to the influence of pressure and temperature. Composition appears to play a dominant role in the type of stacking, and semi-quantitative structural arguments appear to support this contention. The influence of growth mechanism is discussed. A scheme for the identification of the mica polymorphs by X-ray powder and single-crystal methods is given.

scholarly journals Dynamics of Singular Vectors in the Semi-Infinite Eady Model: Nonzero β but Zero Mean PV Gradient

2006 ◽  
Vol 63 (2) ◽  
pp. 547-564 ◽  
Author(s):  
H. de Vries ◽  
J. D. Opsteegh
Keyword(s):  
Kinetic Energy ◽  
Potential Temperature ◽  
Vertical Shear ◽  
Buoyancy Frequency ◽  
Resonant Level ◽  
Frequency Profile ◽  
First Case ◽  
State Potential ◽  
Surface Buoyancy ◽  
Pv Gradient

Abstract A nonmodal approach based on the potential vorticity (PV) perspective is used to compute the singular vector (SV) that optimizes the growth of kinetic energy at the surface for the β-plane Eady model without an upper rigid lid. The basic-state buoyancy frequency and zonal wind profile are chosen such that the basic-state PV gradient is zero. If the f-plane approximation is made, the SV growth at the surface is dominated by resonance, resulting from the advection of basic-state potential temperature (PT) by the interior PV anomalies. This resonance generates a PT anomaly at the surface. The PV unshielding and PV–PT unshielding contribute less to the final kinetic energy at the surface. The general conclusion of the present paper is that surface cyclogenesis (of the 48-h SV) is stronger if β is included. Three cases have been considered. In the first case, the vertical shear of the basic state is modified in order to retain the zero basic-state PV gradient. The increased shear enhances SV growth significantly first because of a lowering of the resonant level (enhanced resonance), and second because of a more rapid PV unshielding process. Resonance is the most important contribution at optimization time. In the second case, the buoyancy frequency of the basic state is modified. The surface cyclogenesis is stronger than in the absence of β but less strong than if the shear is modified. It is shown that the effect of the modified buoyancy frequency profile is that PV unshielding occurs more efficiently. The contribution from resonance to the SV growth remains almost the same. Finally, the SV is calculated for a more realistic buoyancy frequency profile based on observations. In this experiment the increased value of the surface buoyancy frequency reduces the SV growth significantly as compared to the case in which the surface buoyancy frequency takes a standard value. All growth mechanisms are affected by this change in the surface buoyancy frequency.

Analysis of Handling Stresses in Thin Solar Silicon Wafers Generated by a Rigid Vacuum Gripper

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Hao Wu ◽  
Shreyes N. Melkote
Keyword(s):  
Stress Distribution ◽  
Dominant Role ◽  
High Stress ◽  
Surface Profile ◽  
Silicon Wafers ◽  
Wafer Surface ◽  
Initial Surface ◽  
Fe Modeling ◽  
Solar Silicon ◽  
Surface Profiles

Breakage of thin solar silicon wafers during handling and transport depends on the stresses imposed on the wafer by the handling/transport device. In this paper, the stresses generated in solar silicon wafers by a rigid vacuum gripper are analyzed via a combination of experiments and numerical modeling. Specifically, stresses produced in monocrystalline (Cz) and multicrystalline (Cast) silicon wafers of different thicknesses when handled by a vacuum gripper are analyzed using the finite element (FE) method. With the measured surface profiles of the wafer and the gripper as input, the handling process is simulated using FE modeling and the stress distribution obtained. The FE modeling results are validated by experimental data of wafer surface profile during handling. The results show that while the vacuum level does not have significant impact on the stress distribution, the initial surface profiles of the thin wafer and gripper play a dominant role in producing regions of high stress in the wafer.

scholarly journals Contribution of horizontal and vertical advection to the formation of small-scale vertical structures of ozone in the lower and middle stratosphere at Fairbanks, Alaska

2019 ◽  
Author(s):  
Miho Yamamori ◽  
Yasuhiro Murayama ◽  
Kazuo Shibasaki ◽  
Isao Murata ◽  
Kaoru Sato
Keyword(s):  
Dominant Role ◽  
Potential Temperature ◽  
Vertical Gradient ◽  
Small Scale ◽  
Mixing Ratio ◽  
Horizontal Advection ◽  
Vertical Advection ◽  
Background Ozone ◽  
Using Data ◽  
Middle Stratosphere

Abstract. The contribution of vertical and horizontal advection to the production of small-scale vertical ozone structures was investigated using data from an ozonesonde observation performed at intervals of 3 h in Fairbanks (64.8N, 147.9W), Alaska. The dominant vertical scales of the ozone mixing ratio were determined to be 2–5 km, which were similar to those of horizontal winds and the temperature of the lower and middle stratosphere, using spectral analysis. Ozone fluctuations due to vertical advection were estimated from the potential temperature fluctuation and vertical gradient of the background ozone mixing ratio. Residual ozone fluctuations are attributed to horizontal advection. Fluctuations due to horizontal advection are dominant, as reported in previous studies. The cross-correlation of the effects of vertical and horizontal advection was also evaluated. The correlation is relatively larger at altitudes of 18–23 km and 32–33 km compared to those at other height regions. In contrast to previous studies, horizontal advection by gravity waves seems to play a dominant role in the production of small-scale ozone structures at altitudes of 32–35 km.

scholarly journals IMPERATIVES OF COMPLEMENTARITY OF AGRO-FOOD ENTERPRISES ECONOMIC POTENTIAL IMPLEMENTATION

2019 ◽  
pp. 133-140
Author(s):  
Vira Lebedieva ◽  
Tetiana Shabatura ◽  
Mariia Varhatiuk
Keyword(s):  
Dominant Role ◽  
Synergetic Effect ◽  
Building Blocks ◽  
Economic Potential ◽  
Agricultural Enterprises ◽  
Complementary Effect ◽  
Complementary Approach ◽  
Complementary Role ◽  
Structural Blocks

Introduction. Today there are deep economic transformations in Ukraine that necessitate the integration of innovative approaches and methods in the process of implementing the economic potential of agro-food enterprises, in particular the use of an innovative complementary approach. Purpose. The article aims to uncover the peculiarities of integration and the use of imperative of complementarity in the process of implementing the economic potential of agricultural enterprises. Results. Significant advantages and perspectives of the imperatives of the complementarity of the sale of agro-food enterprises are revealed in the achievement of the complementary effect, which, unlike the synergetic effect, ensures the development of two independent structure-building blocks of the enterprise's economic potential by using only one of the resource flows, while obtaining a synergistic effect is possible based on the application of various resources. The expediency of using the imperatives of complementarity of the implementation of the economic potential of agro-food enterprises is justified by the linear and hierarchical nature of their integration. Thus, the linear nature of the integration of complementary imperatives reveals signs of interaction and complementarity between the basic elements of structural units of the economic potential of agro-food enterprises, whereas hierarchical character indicates the dominant role of one and complementary role of other basic elements, which ensures achievement of the priority goals of realization of economic potential of the enterprise. Thus, in the process of implementing the economic potential of agro-food enterprises on the basis of complementarity, we should consider the effects of interaction and complementarity of the flow of its structural blocks, the possibilities of their efficient use and the ability to increase competitive advantages that will ensure achievement of the priority goals of realization of the economic potential of the enterprise, namely, maximization market value of business.

Technological capability and technology management

2014 ◽  
Vol 8 (2) ◽  
pp. 180-200 ◽  
Author(s):  
Weiwei Wu ◽  
Tan Li ◽  
Bo Yu ◽  
Jiliang Wang
Keyword(s):  
Technology Management ◽  
Growth Mechanism ◽  
Positive Feedback ◽  
Order Parameter ◽  
Industrial Development ◽  
Dominant Role ◽  
Telecommunications Industry ◽  
Technological Capability ◽  
Analysis Model ◽  
Content Type

Purpose – The purpose of this paper is to investigate the impacts of technological capability (TC) and technology management (TM) on the development of China’s telecommunications industry by examining two interrelated questions: Which is the order parameter for China’s telecommunications industry? and What are the relationships between TC and TM? The paper will develop models to analyze TC, TM and the development of China’s telecommunications industry quantitatively. Design/methodology/approach – The paper reviews literature related to TC and TM and investigates the technical features of China’s telecommunications industry. Then, the paper makes a theoretical analysis of the relationships among them. First, it analyzes the effects of TC and TM on the industry and tries to explore the order parameter. Second, the paper analyzes the interaction between TC and TM. Then, the paper applies the Haken model to construct an analysis model. It also constructs models for measuring TC and TM. Using the data of China’s telecommunications industry from 1991 to 2010, the paper identifies the order parameter for the industry and tests the relationships between TC and TM. Findings – The paper finds that TC plays a dominant role in the development of China’s telecommunications industry. The paper also finds that TC promotes the development of TM. However, TM fails to promote the development of TC. The paper presents two other important findings. The first one is that China’s telecommunications industry has constructed a positive feedback mechanism for continuous development of TC, which provides an impetus for industry upgrades and development. The second one is that there is no positive feedback growth mechanism for TM capability, which has increased the lag between TM and TC and has become one of the important reasons why TM does not promote TC. Research limitations/implications – Theoretical and managerial implications are put forward. Thus, TC must be improved to propel the development of China’s telecommunications industry; TM should be greatly improved and an effective growth mechanism for TM should be constructed; the synergy between TM and TC should be achieved. Research limitations are also pointed out. Thus, the results in this paper probably cannot be generalized to other industries; it does go on to discuss the synergetic mode of TM and TC that can best compel industrial development, and it does not explain what the growth mechanisms for TM and TC should be. Originality/value – The paper is original, as it provides new perspectives of TM and TC for analyzing industrial development, and it provides the method and model for quantitatively analyzing TC and TM at an industry level. It discovers the order parameter and new problems of China’s telecommunications industry, which no one has identified before. The paper also offers references for analyzing other industries from the perspectives of TM and TC.

Surface quasi-geostrophic dynamics

1995 ◽  
Vol 282 ◽  
pp. 1-20 ◽  
Author(s):  
Isaac M. Held ◽  
Raymond T. Pierrehumbert ◽  
Stephen T. Garner ◽  
Kyle L. Swanson
Keyword(s):  
Potential Temperature ◽  
Edge Wave ◽  
Distinctive Features ◽  
Wave Characteristics ◽  
Inverse Energy Cascade ◽  
System A ◽  
Start Up ◽  
Two Dimensional Flow ◽  
Secondary Instabilities

The dynamics of quasi-geostrophic flow with uniform potential vorticity reduces to the evolution of buoyancy, or potential temperature, on horizontal boundaries. There is a formal resemblance to two-dimensional flow, with surface temperature playing the role of vorticity, but a different relationship between the flow and the advected scalar creates several distinctive features. A series of examples are described which highlight some of these features: the evolution of an elliptical vortex; the start-up vortex shed by flow over a mountain; the instability of temperature filaments; the ‘edge wave’ critical layer; and mixing in an overturning edge wave. Characteristics of the direct cascade of the tracer variance to small scales in homogeneous turbulence, as well as the inverse energy cascade, are also described. In addition to its geophysical relevance, the ubiquitous generation of secondary instabilities and the possibility of finite-time collapse make this system a potentially important, numerically tractable, testbed for turbulence theories.

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