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Varying
Kinds of Varying Terms modified by Varying Selected AbstractsEffects of vegetation on channel morphodynamics: results and insights from laboratory experimentsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2010Michal Tal Abstract A series of laboratory experiments demonstrates that riparian vegetation can cause a braided channel to self-organize to, and maintain, a dynamic, single-thread channel. The initial condition for the experiments was steady-state braiding in non-cohesive sand under uniform discharge. From here, an experiment consisted of repeated cycles alternating a short duration high flow with a long duration low flow, and uniform dispersal of alfalfa seeds over the bed at the end of each high flow. Plants established on freshly deposited bars and areas of braidplain that were unoccupied during low flow. The presence of the plants had the effect of progressively focusing the high flow so that a single dominant channel developed. The single-thread channel self-adjusted to carry the high flow. Vegetation also slowed the rate of bank erosion. Matching of deposition along the point bar with erosion along the outer bend enabled the channel to develop sinuosity and migrate laterally while suppressing channel splitting and the creation of new channel width. The experimental channels spontaneously reproduced many of the mechanisms by which natural meandering channels migrate and maintain a single dominant channel, in particular bend growth and channel cutoff. In contrast with the braided system, where channel switching is a nearly continuous process, vegetation maintained a coherent channel until wholesale diversion of flow via cutoff and/or avulsion occurred, by which point the previous channel tended to be highly unfavorable for flow. Thus vegetation discouraged the coexistence of multiple channels. Varying discharge was key to allowing expression of feedbacks between the plants and the flow and promoting the transition from braiding to a single-thread channel that was then dynamically maintained. Copyright © 2010 John Wiley & Sons, Ltd. [source] The Output Effect of a Transition to Price Stability When Velocity Is Time VaryingJOURNAL OF MONEY, CREDIT AND BANKING, Issue 5 2010LYNNE EVANS price stability; velocity; disinflation; output boom; optimal speed of disinflation This paper explores the effect of time-varying velocity on output responses to policies for reducing/stopping inflation. We study a dynamic general equilibrium model with sticky prices in which we introduce time-varying velocity. Specifically, we endogenize time-varying velocity into the model developed by Ireland (1997) for analyzing optimal disinflation. The nonlinear solution method reveals that, depending on velocity, the "disinflationary boom" found by Ball (1994) may disappear even under perfect credibility and that early output losses may be much larger than previously thought. Indeed, we find that a gradual disinflation from a low inflation may even be undesirable. [source] Flexibility in Proteins: Tuning the Sensitivity to O2 Diffusion by Varying the Lifetime of a Phosphorescent Sensor in Horseradish Peroxidase,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2004Janna Nibbs ABSTRACT The heme in horseradish peroxidase (HRP) was replaced by phosphorescent Pt-mesoporphyrin IX (PtMP), which acted as a phosphorescent marker of oxygen quenching and allowed comparison with another probe, Pd-mesoporphyrin IX (Khajehpour et al. (2003) Proteins 53, 656,666). Benzohydroxamic acid (BHA), a competitive inhibitor of the enzyme, was also used to monitor its effects on phosphorescence quenching. With the addition of BHA, in the presence of oxygen, the phosphorescence intensity of the protein increased. In contrast, the addition of BHA, in the absence of oxygen, reduced the phosphorescence intensity of the protein. Kd= 18 ,M when BHA binds to PtMP-HRP. The effect of BHA can be explained by two factors: (1) BHA reduces the accessibility of O2 to the protein interior and (2) BHA itself quenches the phosphorescence. Consistent with this, the oxygen quenching of the phosphorescence of PtMP-HRP gave a quenching constant of kq= 234 mm Hg,1 s,1 in the absence of BHA and kq= 28.7 mm Hg,1 s,1 in the presence of BHA. The quenching rate of BHA is 4000 s,1. The relative quantum yield of the phosphorescence of the Pt derivative is about six times that of the Pd derivative, whereas the phosphorescence lifetime is approximately eight times shorter. The high quantum yield and suitable lifetime make Pt-porphyrins appropriate as sensors of O2 diffusion and flexibility in heme proteins. [source] Stability of Linear Parameter Varying and Linear Switching SystemsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003Fabian Wirth We consider stability of families of linear time-varying systems, that are determined by a set of time-varying parameters which adhere to certain rules. The conditions are general enough to encompass on the one hand stability questions for systems that are frequently called linear parameter varying systems in the literature and on the other hand also linear switching systems, in which parameter variations are allowed to have discontinuities. Combinations of these two sets of assumptions are also possible within the framework studied here. Under the assumption of irreducibility of the sets of system matrices, we show how to construct parameter dependent Lyapunov functions for the systems under consideration that exactly characterize the exponential growth rate. It is clear that such Lyapunov functions do not exist in general. But every system of our class can be reduced to a finite number of subsystems for which irreducibility holds. [source] The Relative Importance of Interfirm Relationships and Knowledge Transfer for New Product Development Success,THE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 2 2007Mette Praest Knudsen The relationship and network literature has primarily focused on particular partner types, for example, buyer,supplier relationships or competitor interaction. This article explores the nature and relative importance of different types of interfirm relationships for new product development (NPD) success. The underlying premise of the study is that not only the type of interfirm relationships but also the combination of relationships are important for NPD performance. The interaction with a specific type of partner is expected to influence innovative performance by means of appropriate knowledge transfer. Varying needs for external knowledge, and thus types of relationships, are observed depending on the particular stages in the NPD process, the character of the knowledge base of the firm, and the industrial conditions. The absorption of external knowledge is discussed using the degree of redundancy in knowledge, which is defined as the degree of overlap in the knowledge base of the sender and the recipient of knowledge. Hence, the degree of redundancy has direct implications for the ease and, hence, use of knowledge shared with an external partner. The article is based on data from the Know for Innovation survey on innovative activities among European firms, which was carried out in 2000 in seven European countries covering five industries. The article explores the extent of use of external relationships in collaborative product development and finds that customers are involved more frequently in joint development efforts. Second, the industry association of the most important relationship is studied, and the results show that firms tend to partner with firms from their own industry. The danger in this approach is that firms from their own industry tend to contribute similar knowledge, which ultimately may endanger the creation of new knowledge and therefore more radical product developments. The analyses combine the finding that relationships with customers are used most frequently at both early and late stages of the product development process, with a second and more contradictory finding that at the same time customer relationships have a negative impact on innovative success. Moreover, the combination of customers, with both universities and competitors, has a significant negative effect on innovative performance. The potential causes of this apparent paradox can be narrowed down to two: (1) the average customer may be unable to articulate needs for advanced technology-based products; and (2) the average customer may be unable to conceptualize ideas beyond the realm of his or her own experience. Based on this evidence the article cautions product development managers to think explicitly about what certain customers can contribute with and, more importantly, to match this contribution directly with their own sense of what direction product development should go in the future. Finally, the role of complementary as well as supplementary knowledge is investigated for innovative success finding that sharing of supplementary knowledge with external partners in NPD leads to a positive effect on innovative performance. The article is concluded by a discussion of the implication of this finding for building knowledge within the firm and for selecting external partners for NPD. [source] Layered Performance Animation with Correlation MapsCOMPUTER GRAPHICS FORUM, Issue 3 2007Michael Neff Abstract Performance has a spontaneity and "aliveness" that can be difficult to capture in more methodical animation processes such as keyframing. Access to performance animation has traditionally been limited to either low degree of freedom characters or required expensive hardware. We present a performance-based animation system for humanoid characters that requires no special hardware, relying only on mouse and keyboard input. We deal with the problem of controlling such a high degree of freedom model with low degree of freedom input through the use of correlation maps which employ 2D mouse input to modify a set of expressively relevant character parameters. Control can be continuously varied by rapidly switching between these maps. We present flexible techniques for varying and combining these maps and a simple process for defining them. The tool is highly configurable, presenting suitable defaults for novices and supporting a high degree of customization and control for experts. Animation can be recorded on a single pass, or multiple layers can be used to increase detail. Results from a user study indicate that novices are able to produce reasonable animations within their first hour of using the system. We also show more complicated results for walking and a standing character that gestures and dances. [source] Dynamic Textures for Image-based Rendering of Fine-Scale 3D Structure and Animation of Non-rigid MotionCOMPUTER GRAPHICS FORUM, Issue 3 2002Dana Cobza The problem of capturing real world scenes and then accurately rendering them is particularly difficult for fine-scale 3D structure. Similarly, it is difficult to capture, model and animate non-rigid motion. We present a method where small image changes are captured as a time varying (dynamic) texture. In particular, a coarse geometry is obtained from a sample set of images using structure from motion. This geometry is then used to subdivide the scene and to extract approximately stabilized texture patches. The residual statistical variability in the texture patches is captured using a PCA basis of spatial filters. The filters coefficients are parameterized in camera pose and object motion. To render new poses and motions, new texture patches are synthesized by modulating the texture basis. The texture is then warped back onto the coarse geometry. We demonstrate how the texture modulation and projective homography-based warps can be achieved in real-time using hardware accelerated OpenGL. Experiments comparing dynamic texture modulation to standard texturing are presented for objects with complex geometry (a flower) and non-rigid motion (human arm motion capturing the non-rigidities in the joints, and creasing of the shirt). Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Image Based Rendering [source] A Study on the Effects of Damage Models and Wavelet Bases for Damage Identification and Calibration in BeamsCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 8 2007Vikram Pakrashi A numerical study has been performed in this article addressing these issues for single and multispan beams with an open crack. The first natural modeshapes of single and multispan beams with an open crack have been simulated considering damage models of different levels of complexity and analyzed for different crack depth ratios and crack positions. Gaussian white noise has been synthetically introduced to the simulated modeshape and the effects of varying signal-to-noise ratio have been studied. A wavelet-based damage identification technique has been found to be simple, efficient, and independent of damage models and wavelet basis functions, once certain conditions regarding the modeshape and the wavelet bases are satisfied. The wavelet-based damage calibration is found to be dependent on a number of factors including damage models and the basis function used in the analysis. A curvature-based calibration is more sensitive than a modeshape-based calibration of the extent of damage. [source] A North American multilaboratory study of CD4 counts using flow cytometric panleukogating (PLG): A NIAID-DAIDS Immunology Quality Assessment Program Study,,§¶CYTOMETRY, Issue S1 2008Thomas N. Denny Abstract Background The global HIV/AIDS pandemic and guidelines for initiating anti-retroviral therapy (ART) and opportunistic infection prophylaxis demand affordable, reliable, and accurate CD4 testing. A simple innovative approach applicable to existing technology that has been successfully applied in resource-challenged settings, PanLeukogated CD4 (PLG), could offer solutions for cost saving and improved precision. Methods Day-old whole blood from 99 HIV+ donors was simultaneously studied in five North-American laboratories to compare the performance of their predicate methods with the dual-platform PLG method. The predicate technology included varying 4-color CD45/CD3/CD4/CD8 protocols on different flow cytometers. Each laboratory also assayed eight replicate specimens of day-old blood from 10 to 14 local donors. Bias and precision of predicate and PLG methods was studied between- and within-participating laboratories. Results Significantly (P < 0.0001) improved between-laboratory precision/coefficient of variation (CV%) was noted using the PLG method (overall median 9.3% vs. predicate median CV 13.1%). Within-laboratory precision was also significantly (P < 0.0001) better overall using PLG (median 4.6% vs. predicate median CV 6.2%) and in 3 of the 5 laboratories. PLG counts tended to be 11% smaller than predicate methods (P < 0.0001) for shipped (median of predicate,PLG = 31) and local specimens (median of predicate,PLG = 23), both overall and in 4 of 5 laboratories (median decreases of 4, 16, 20, and 21% in shipped specimens); the other laboratory had a median increase of 5%. Conclusion Laboratories using predicate CD4 methods similar to those in this study could improve their between-laboratory and their within-laboratory precision, and reduce costs, by switching to the PLG method after adequate training, if a change (usually, a decrease) in CD4 counts is acceptable to their health systems. © 2008 Clinical Cytometry Society [source] Mohs Micrographic Surgery for Lentigo Maligna and Lentigo Maligna Melanoma using Mel-5 Immunostaining: University of Minnesota ExperienceDERMATOLOGIC SURGERY, Issue 5 2006SACHIN S. BHARDWAJ MD BACKGROUND Mohs micrographic surgery (MMS) continues to become a more common and accepted treatment for lentigo maligna (LM) and lentigo maligna melanoma (LMM). The primary difficulty encountered lies in the accurate identification of atypical single melanocytes to determine tumor-free margins. Numerous methods have been used to better visualize single melanocytes, with varying results. We present our experience using Mel-5 immunostaining in MMS of LM and LMM. METHODS Two hundred patients with primary or recurrent LM or LMM were treated using MMS from 1999 to 2003 at the University of Minnesota. The initial clinical margins were determined by Wood's light examination, and an initial debulk specimen was taken and sent for formalin fixation and later reviewed by a dermatopathologist. The first Mohs layer was then taken, and staining with hemotoxylin and eosin as well as Mel-5 immunostaining was performed. All patients were followed up to evaluate for recurrence, with a mean follow-up time of 38.4 months. RESULTS Of the 200 patients treated, only one recurrence was noted. This patient had been treated with excision followed by radiation before MMS. Use of Mel-5 immunostaining added approximately 40 minutes to each stage. Use of the Autostainer Immunostaining System (DAKO, Carpenterina, CA, USA) shortened the added time to 20 minutes. CONCLUSIONS MMS with Mel-5 immunostaining yielded excellent results in the treatment of LM and LMM, with only one recurrence noted in 200 patients. When an automated immunostainer was used, minimal time was added to each Mohs stage. [source] Estimating the spatiotemporal pattern of volumetric growth rate from fate maps in chick limb developmentDEVELOPMENTAL DYNAMICS, Issue 2 2009Yoshihiro Morishita Abstract Morphogenesis is achieved through volumetric growth of tissue at a rate varying over space and time. The volumetric growth rate of each piece of tissue reflects the behaviors of constituent cells such as cell proliferation and death. Hence, clarifying its spatiotemporal pattern accurately is a key to bridge between cell behaviors and organ morphogenesis. We here propose a new method to estimate the spatiotemporal pattern of volumetric growth rate from fate map data with limited resolution on space and time by using a mathematical model. We apply the method to chick wing data along the proximodistal axis, and find that the volumetric growth pattern is biphasic: it is spatially uniform in earlier stages (until stage 23), but in later stages the volumetric growth occurs approximately 4.5 times as fast as in the distal region (within approximately 100 ,m from the limb tip) than in the proximal region. Developmental Dynamics 238:415,422, 2009. © 2009 Wiley-Liss, Inc. [source] Unusual synchronization of Red Sea fish energy expendituresECOLOGY LETTERS, Issue 2 2003Lewi Stone Abstract The highly gregarious goat fish Parupeneus forskalii found in the Red Sea at Eilat, Israel exhibit highly synchronous swimming and feeding activity. Five fish were studied under controlled conditions and highly resolved time-series of their energy expenditures were measured. All fish demonstrated strong phase synchronization in that their activity levels, although erratic in time and intensity, were collectively coordinated and peaked simultaneously together. The synchronization of these wildly varying, and possibly chaotic signals of energy expenditures, were quantified using phase analysis. We suggest that, ecologically, this collective synchronization is a strategy that increases food-catch. [source] Dual-asymmetry electrokinetic flow focusing for pre-concentration and analysis of catecholamines in CE electrochemical nanochannelsELECTROPHORESIS, Issue 14 2009Ren-Guei Wu Abstract In this research, a technique incorporating dual-asymmetry electrokinetic flow (DAEKF) was applied to a nanoCE electrochemical device for the pre-concentration and detection of catecholamines. The DAEKF was constructed by first generating a ,-potential difference between the top and bottom walls, which had been pre-treated with O2 and H2O surface plasma, respectively, yielding a 2-D gradient shear flow across the channel depth. The shear flow was then exposed to a varying ,-potential along the downstream direction by control of the field-effect in order to cause downward rotational flow in the channel. By this mechanism, almost all of the samples were effectively brought down to the electrode surface for analysis. Simulations were carried out to reveal the mechanism of concentration caused by the DAEKF, and the results reasonably describe our experiment findings. This DAEKF technique was applied to a glass/glass CE electrochemical nanochip for the analysis of catecholamines. The optimum detection limit was determined to be 1.25 and 3.3,nM of dopamine and catechol, respectively. A detection limit at the zeptomole level for dopamine can be obtained in this device, which is close to the level released by a single neuron cell in vitro. [source] Examining the use of subsidies for the abatement of greenhouse gas emissions through experimental simulationsENVIRONMENTAL POLICY AND GOVERNANCE, Issue 4 2006Lars E. Olsson Abstract A market experiment was designed to empirically investigate the potential effectiveness of a governmental subsidy system to reduce sales and therefore production of environmentally harmful products. The important issue of whether the subsidy system preserves competitiveness was also examined. In the experiment two levels of a subsidy for unsold units were compared with no subsidy. To simulate the way in which subsidy levels may vary across time in real markets, the effects of high and low uncertainty regarding the subsidy level were also investigated. The results showed that subsidies, whether known and fixed or uncertain and varying, did not erode competition but nevertheless led to higher prices, which resulted in fewer sales. In the control condition a price war resulting in decreasing prices and increasing sales were observed. Several ways in which the proposed subsidy system may be implemented in the transport sector and other sectors are discussed. It is suggested that subsidies may make the adjustment process toward sustainable production less costly for the regulated parties. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment. [source] A systematic review of impulsivity in eating disordersEUROPEAN EATING DISORDERS REVIEW, Issue 6 2009Samantha E. Waxman Abstract The purpose of this paper is to conduct a systematic review of the current literature that examines impulsivity in individuals with eating disorders (ED). Studies were obtained from Embase, Pubmed and Psycinfo, and were included if they assessed impulsivity in individuals over 18 years of age with an ED diagnosis and published in the last 10 years. The methodological quality of the studies was rated. Twelve studies were included in this review, with methodological quality varying across studies. Findings suggest that impulsivity is best assessed multi-modally, with a combination of self-report, behavioural and physiological measures. In general, impulsivity was found to differentiate individuals with EDs from controls, as well as across diagnostic subtypes. The current findings have important clinical implications for our understanding and treatment of both impulsivity and eating disorders. Copyright © 2009 John Wiley & Sons, Ltd and Eating Disorders Association. [source] Anatomy of executive deficit following ruptured anterior communicating artery aneurysmEUROPEAN JOURNAL OF NEUROLOGY, Issue 5 2009O. Martinaud Background and purpose:, To evaluate behavioral and cognitive deficits following anterior communicating artery aneurysm rupture and determine critical lesion locations. Methods:, We investigated 74 patients with standardized cognitive tests and behavioral inventory. Two examiners rated MRI signal abnormalities in 51 predetermined regions of interest. Classification tree analysis was used to select regions associated with each cognitive deficit. Results:, Eleven patients presented behavioral executive deficits and 10 had cognitive executive deficit. Their presence depended on left hemisphere lesions only: (i) ventral striatum lesion was associated with behavioral executive deficit (P = 0.04), reduction of activities (P = 0.01), and hyperactivity (P = 0.02); (ii) superior frontal gyrus lesion, with cognitive executive deficit (P = 0.01), action initiation deficit (P = 0.02), and rule deduction deficit (P = 0.02); (iii) anterior half of centrum semiovale lesion, with Stroop inhibition deficit (P = 0.02); (iv) medial superior and middle frontal gyri lesions, with task coordination deficit (P = 0.01); and (v) middle frontal gyrus lesion, with words generation deficit (P = 0.02). Conclusion:, This study supports that (i) cognitive executive deficits depend mostly on lateral prefrontal lesions, (ii) with locations varying according to executive process, and (iii) behavioral executive deficits are mainly due to left ventral striatum lesion in post-aneurysmal damage. [source] The Effect of Nanoparticle Shape on the Photocarrier Dynamics and Photovoltaic Device Performance of Poly(3-hexylthiophene):CdSe Nanoparticle Bulk Heterojunction Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Smita Dayal Abstract The charge separation and transport dynamics in CdSe nanoparticle:poly(3-hexylthiophene) (P3HT) blends are reported as a function of the shape of the CdSe-nanoparticle electron acceptor (dot, rod, and tetrapod). For optimization of organic photovoltaic device performance it is crucial to understand the role of various nanostructures in the generation and transport of charge carriers. The sample processing conditions are carefully controlled to eliminate any processing-related effects on the carrier generation and on device performance with the aim of keeping the conjugated polymer phase constant and only varying the shape of the inorganic nanoparticle acceptor phase. The electrodeless, flash photolysis time-resolved microwave conductivity (FP-TRMC) technique is used and the results are compared to the efficiency of photovoltaic devices that incorporate the same active layer. It is observed that in nanorods and tetrapods blended with P3HT, the high aspect ratios provide a pathway for the electrons to move away from the dissociation site even in the absence of an applied electric field, resulting in enhanced carrier lifetimes that correlate to increased efficiencies in devices. The processing conditions that yield optimum performance in high aspect ratio CdSe nanoparticles blended with P3HT result in poorly performing quantum dot CdSe:P3HT devices, indicating that the latter devices are inherently limited by the absence of the dimensionality that allows for efficient, prolonged charge separation at the polymer:CdSe interface. [source] Present status, and social and economic significance of inland fisheries in GermanyFISHERIES MANAGEMENT & ECOLOGY, Issue 4-5 2001H. Wedekind The Federal Republic of Germany is situated in the central part of Europe and covers an area of 358 000 km2. The climate is maritime in the north and continental in the south with precipitation varying between 600 and 2000 mm year,1. Lakes and farm ponds are common in the north-eastern part of the country and in the alpine and pre-alpine regions to the south. A great number of small natural and artificial water bodies exist all over the country. There are about 800 000 ha of inland waters. The population of 82 million people are concentrated around a number of large conurbations. Over the last 150 years, intense use of the water resources by industry led to pollution and a severe decrease in river and lake fisheries. Only 587 inland fishing enterprises still existed in the early 1990s. Catches from commercial fisheries are decreasing with a total of 3469 t being caught in 1998. The Lake Constance fishery, which landed about 840 t in 1998, is an exception to the general trend. Strong competition for the aquatic resource is affecting commercial fisheries, whilst recreational fisheries have gained increasing importance over the last decades. Recent studies provided basic information on anglers' habits, social structure and economic significance as well as their effects on the waters. Aquaculture mainly produces rainbow trout, Oncoryhnchus mykiss (Walbaum) 20 000 t and carps (12 000 t) e.g. Cyprinus carpio L. Despite pressures from industry and conservation movements, regional support for fisheries and their development has intensified, leading to improved water quality. There are even attempts to re-establish abandoned fisheries. Co-operation with conservationists provides an opportunity for the future survival and development of fisheries. The fisheries and aquaculture sectors changed drastically after the reunification of Germany. The collapse of the infrastructure in the eastern part of Germany led to a decline in production and to a special investigation on recent developments of this sector. [source] Interpretation of observed fluid potential patterns in a deep sedimentary basin under tectonic compression: Hungarian Great Plain, Pannonian BasinGEOFLUIDS (ELECTRONIC), Issue 1 2001J. Tóth Abstract The , 40 000 km2 Hungarian Great Plain portion of the Pannonian Basin consists of a basin fill of 100 m to more than 7000 m thick semi- to unconsolidated marine, deltaic, lacustrine and fluviatile clastic sediments of Neogene age, resting on a strongly tectonized Pre-Neogene basement of horst-and-graben topography of a relief in excess of 5000 m. The basement is built of a great variety of brittle rocks, including flysch, carbonates and metamorphics. The relatively continuous Endr,d Aquitard, with a permeability of less than 1 md (10,15 m2) and a depth varying between 500 and 5000 m, divides the basin's rock framework into upper and lower sequences of highly permeable rock units, whose permeabilities range from a few tens to several thousands of millidarcy. Subsurface fluid potential and flow fields were inferred from 16 192 water level and pore pressure measurements using three methods of representation: pressure,elevation profiles; hydraulic head maps; and hydraulic cross-sections. Pressure,elevation profiles were constructed for eight areas. Typically, they start from the surface with a straight-line segment of a hydrostatic gradient (,st = 9.8067 MPa km,1) and extend to depths of 1400,2500 m. At high surface elevations, the gradient is slightly smaller than hydrostatic, while at low elevations it is slightly greater. At greater depths, both the pressures and their vertical gradients are uniformly superhydrostatic. The transition to the overpressured depths may be gradual, with a gradient of ,dyn = 10,15 MPa km,1 over a vertical distance of 400,1000 m, or abrupt, with a pressure jump of up to 10 MPa km,1 over less than 100 m and a gradient of ,dyn > 20 MPa km,1. According to the hydraulic head maps for 13 100,500 m thick horizontal slices of the rock framework, the fluid potential in the near-surface domains declines with depth beneath positive topographic features, but it increases beneath depressions. The approximate boundary between these hydraulically contrasting regions is the 100 m elevation contour line in the Duna,Tisza interfluve, and the 100,110 m contours in the Nyírség uplands. Below depths of ,,600 m, islets of superhydrostatic heads develop which grow in number, areal extent and height as the depth increases; hydraulic heads may exceed 3000 m locally. A hydraulic head ,escarpment' appears gradually in the elevation range of ,,1000 to ,,2800 m along an arcuate line which tracks a major regional fault zone striking NE,SW: heads drop stepwise by several hundred metres, at places 2000 m, from its north and west sides to the south and east. The escarpment forms a ,fluid potential bank' between a ,fluid potential highland' (500,2500 m) to the north and west, and a ,fluid potential basin' (100,500 m) to the south and east. A ,potential island' rises 1000 m high above this basin further south. According to four vertical hydraulic sections, groundwater flow is controlled by the topography in the upper 200,1700 m of the basin; the driving force is orientated downwards beneath the highlands and upwards beneath the lowlands. However, it is directed uniformly upwards at greater depths. The transition between the two regimes may be gradual or abrupt, as indicated by wide or dense spacing of the hydraulic head contours, respectively. Pressure ,plumes' or ,ridges' may protrude to shallow depths along faults originating in the basement. The basement horsts appear to be overpressured relative to the intervening grabens. The principal thesis of this paper is that the two main driving forces of fluid flow in the basin are gravitation, due to elevation differences of the topographic relief, and tectonic compression. The flow field is unconfined in the gravitational regime, whereas it is confined in the compressional regime. The nature and geometry of the fluid potential field between the two regimes are controlled by the sedimentary and structural features of the rock units in that domain, characterized by highly permeable and localized sedimentary windows, conductive faults and fracture zones. The transition between the two potential fields can be gradual or abrupt in the vertical, and island-like or ridge-like in plan view. The depth of the boundary zone can vary between 400 and 2000 m. Recharge to the gravitational regime is inferred to occur from infiltrating precipitation water, whereas that to the confined regime is from pore volume reduction due to the basement's tectonic compression. [source] Integrating fluxes from heterogeneous vegetationGLOBAL ECOLOGY, Issue 6 2001F. Ian Woodward Abstract The vegetated landscape of Europe has been strongly impacted by human management to produce a heterogeneous patchwork of semi-natural and agricultural vegetation varying over a wide range of spatial scales. A model is described for averaging vegetation fluxes from a landscape of forest and grassland into the planetary boundary layer (PBL). At a scale of 1 km, model simulations indicate that vegetation heterogeneity exerts little effect on the PBL and regional fluxes will be simple areal averages of the different vegetation types. Above 5 km the model simulates significant effects of different vegetation types on the whole PBL. Averaging fluxes to the regional scale will therefore need to consider explicitly the nature, extent and behaviour of different vegetation types. [source] Book-History Approaches to India: Representations of the Subcontinent in the Novel and Verse, 1780,1823HISTORY COMPASS (ELECTRONIC), Issue 2 2010Ashok Malhotra Literary representations of India in verse and novels written by British authors during the period 1780,1823 have been approached by contemporary scholars either from the postcolonial perspective of relating the fiction to the shifting relationship between colonizer or colonized, or to correlating portrayals to elitist political debates taking place within the metropole. The argument proposes that forthcoming scholarship should adopt a book-history approach to the topic which would add an important contextual dimension to the readings of fictional texts and understanding of a whole set of British cultural attitudes towards Indians. To this end, it proposes that further critical analysis of British India fictions could situate recurring tropes about India in relation to the demands and prevailing fashions of the literary marketplace, and determine how the varying perceived cultural status and the internal development of the two literary modes affect portrayals of the subcontinent. [source] Hydrologic prediction for urban watersheds with the Distributed Hydrology,Soil,Vegetation ModelHYDROLOGICAL PROCESSES, Issue 21 2008Lan Cuo Abstract Some relatively straightforward modifications to the Distributed Hydrology,Soil,Vegetation Model (DHSVM) are described that allow it to represent urban hydrological processes. In the modified model, precipitation that falls on impervious surfaces becomes surface runoff, and a spatially varying (depending on land cover) fraction of surface runoff is connected directly to the stream channel, with the remainder stored and slowly released to represent the effects of stormwater detention. The model was evaluated through application to Springbrook Creek watershed in a partially urbanized area of King County, Washington. With calibration, the modified DHSVM simulates hourly streamflow from these urbanized catchments quite well. It is also shown how the revised model can be used to study the effects of continuing urbanization in the much larger Puget Sound basin. Model simulations confirm many previous studies in showing that urbanization increases peak flows and their frequency, and decreases peak flow lag times. The results show that the urbanization parameterizations for DHSVM facilitate use of the model for prediction and/or reconstruction of a range of historic and future changes in land cover that will accompany urbanization as well as other forms of vegetation change. Copyright © 2008 John Wiley & Sons, Ltd. [source] Experimental study of stick-slip behaviourINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 6 2004Florence Adjemian Abstract Simple axi-symmetric uni-axial compression tests have been realized on dry loose samples of glass beads (diameters d: d=0.2 ± 0.05 mm, 0.75 ± 0.1 mm, or 3 mm) and on Hostun sand under small lateral confinement, ,3<60 kPa, using different sample sizes. The experiments with the two smallest spheres (d=0.2 and 0.75 mm) exhibit stick-slips, which are characterized by (i) a rapid release ,q of the deviatoric stress q and by (ii) the strain ,,1 separating two events. The samples which exhibit stick-slip also present a weakening of strength q(,1) as the rate of deformation d,1/dt is increased. No stick-slip is generated during the first part of the q,,1 curve, i.e. when q grows fast with ,1. Four different parameters helped us determine the statistics of ,q and ,,: the lateral pressure ,3,, the rate of deformation d,1/dt, the sample height H, and the diameter D. The statistics do not depend on rate history. They look like exponentials in small samples and/or in (large sample+fast d,1/dt), and they look like Poissonian or Gaussian in (Large sample+small d,1/dt). This change in statistics is attributed to a varying of triggering process starting from a single random event in small samples to multiple random events. We have interpreted this change of statistics as due to some finite size effect so that the representative elementary volume shall contain at least (200)3 grains. Localization of deformation is visible at the end of compression but cannot be detected from stick-slip statistics nor from q vs , curve. Copyright © 2004 John Wiley & Sons, Ltd. [source] Analysis of singular stress fields at multi-material corners under thermal loadingINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2006Chongmin SongArticle first published online: 7 SEP 200 Abstract The scaled boundary finite-element method is extended to the modelling of thermal stresses. The particular solution for the non-homogeneous term caused by thermal loading is expressed as integrals in the radial direction, which are evaluated analytically for temperature changes varying as power functions of the radial coordinate. When applied to model a multi-material corner, only the boundary of the problem domain is discretized. The boundary conditions on the straight material interfaces and the side-faces forming the corner are satisfied analytically without discretization. The stress field is expressed semi-analytically as a series solution. The stress distribution along the radial direction, including both the real and complex power singularity and the power-logarithmic singularity, is represented analytically. The stress intensity factors are determined directly from their definitions in stresses. No knowledge on asymptotic expansions is required. Numerical examples are calculated to evaluate the accuracy of the scaled boundary finite-element method. Copyright © 2005 John Wiley & Sons, Ltd. [source] Robust fault detection and isolation for LPV systems under a sensitivity constraintINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 1 2009Saverio Armeni Abstract A novel fault detection and isolation (FDI) filter design method is proposed for linear parameter varying (LPV) systems. The LPV system description can be used to approximate the behavior of nonlinear systems and leads to simple nonlinear FDI designs. The main goal here is to obtain residual generator (RG) filters with enhanced fault transmission dc-gains and large ,, nuisance attenuation. This is achieved using bilinear matrix inequality techniques by exploiting the relevant geometrical properties of the affine LPV description. Finally, it is shown by a nonlinear example that the RG filters designed by the proposed method compare well with alternative approaches including direct nonlinear design methods. Copyright © 2008 John Wiley & Sons, Ltd. [source] Adaptive robust H, state feedback control for linear uncertain systems with time-varying delayINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 9 2008Dan Ye Abstract This paper considers the problem of adaptive robust H, state feedback control for linear uncertain systems with time-varying delay. The uncertainties are assumed to be time varying, unknown, but bounded. A new adaptive robust H, controller is presented, whose gains are updating automatically according to the online estimates of uncertain parameters. By combining an indirect adaptive control method and a linear matrix inequality method, sufficient conditions with less conservativeness than those of the corresponding controller with fixed gains are given to guarantee robust asymptotic stability and H, performance of the closed-loop systems. A numerical example and its simulation results are given to demonstrate the effectiveness and the benefits of the proposed method. Copyright © 2008 John Wiley & Sons, Ltd. [source] Adaptive backstepping control for a class of time delay systems with nonlinear perturbationsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 3 2008Chang-Chun Hua Abstract The sliding mode control method has been extensively employed to stabilize time delay systems with nonlinear perturbations. Although the resulting closed-loop systems have good transient and steady-state performances, the designed controllers are dependent on the time delays. But one knows that it is difficult to obtain the precise delay time in practical systems, especially when it is time varying. In this paper, we revisit the problem and use the backstepping method to construct the state feedback controller. First, a coordinate transformation is used to obtain a cascade time delay system. Then, a linear virtual control law is designed for the first subsystem. The memoryless controller is further constructed based on adaptive method for the second subsystem with the uncertainties bounded by linear function. By choosing new Lyapunov,Krasovskii functional, we show that the system state converges to zero asymptotically. Via the proposed approach, we also discuss the case that the uncertainties are bounded by nonlinear functions. Finally, simulations are done to verify the effectiveness of the main results obtained. Copyright © 2007 John Wiley & Sons, Ltd. [source] The effect of service quality on trust and commitment varying across generationsINTERNATIONAL JOURNAL OF CONSUMER STUDIES, Issue 4 2009Jinsook E. Cho Abstract We examine the effect of service quality on consumer trust and commitment in the context of obtaining a financial loan and how these relationships vary across different generational cohorts. We find that the service quality offered by a loan officer has a significant effect on consumer trust towards a financial institution, which in turn influences consumer commitment to a financial institution for a future transaction. We also find that relative strengths of a few paths in the model differ across different age cohorts, indicating some generational variability in the relationship between service quality, trust and commitment. [source] Equilibrium moisture content and heat of desorption of saffronINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2010Hamid Reza Gazor Summary The equilibrium moisture contents of saffron (Crocus sativus L.) stigmas were determined experimentally using the standard gravimetric method at temperatures 30, 45 and 60 °C and water activity ranging from 11% to 83%. The sorption isotherm curves of saffron were sigmoidal in shape and decreased with increased temperature at constant relative humidity. Five selected isotherm models GAB, modified Henderson, modified Chung-Pfost, modified Halsaey and modified Oswin were tested to fit the experimental isotherm data. Modified Oswin and modified Henderson models were found acceptable for predicting desorption moisture isotherms and fitting to the experimental data, respectively. The isosteric heats of desorption, determined from equilibrium data using the Clausius-Clapeyron equation, were found to be a function of moisture content. The net isosteric heat of desorption of saffron varied between 1.38 and 5.38 kJ mol,1 at moisture content varying between 2% and 20% (d.b). [source] Robust identification/invalidation in an LPV frameworkINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 3 2010Fernando D. Bianchi Abstract A robust linear parameter varying (LPV) identification/invalidation method is presented. Starting from a given initial model, the proposed method modifies it and produces an LPV model consistent with the assumed uncertainty/noise bounds and the experimental information. This procedure may complement existing nominal LPV identification algorithms, by adding the uncertainty and noise bounds which produces a set of models consistent with the experimental evidence. Unlike standard invalidation results, the proposed method allows the computation of the necessary changes to the initial model in order to place it within the consistency set. Similar to previous LPV identification procedures, the initial parameter dependency is fixed in advance, but here a methodology to modify this dependency is presented. In addition, all calculations are made on state-space matrices which simplifies further controller design computations. The application of the proposed method to the identification of nonlinear systems is also discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||