bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determining Thermal Test Requirements for Automotive Components
Authors: Aldridge Dustin S. 
Published: February 2004

AbstractComponent thermal response is dependent upon numerous factors including the atmospheric temperature, heat sinks and sources, vehicle use time, etc. The number of significant thermal cycles and time at temperature for many components will be related to the number of times the engine is started. This paper provides a methodology to determine the number of significant thermal cycles and time at temperature a product will experience in 10 years which will depend upon engine starts. These calculations provide the basis for an accelerated test requirement to qualify the product based upon customer usage measurements. Because of the trace ability and linkage, the methodology is more marketable to internal and external customers, and less likely to be questioned or arbitrarily overruled. It also enables relative severity assessments for historical customer requirements compared with field needs. Copyright © 2004 John Wiley & Sons, Ltd.
Accelerated Reliability Qualification in Automotive Testing
Authors: Porter Alex 
Published: February 2004

AbstractProducts must come to market quickly, be more reliable and cost less. The problem is that statistical measures take time. There is a clear need for actionable information about the robustness or durability of a product early in the development process. In a Failure Mode Verification Test (FMVT), the analysis is not statistical but is designed to check two assumptions. First, that the design is capable of producing a viable product for the environments applied. Second, that a good design and fabrication of the product would last for a long period of time under all of the stresses that it is expected to see and would accumulate stress damage throughout the product in a uniform way. Testing a product in this way leads to three measures of the product's durability: (1) design maturity, the ratio between time to first failure and the average time between failures after the first failure; (2) technological limit, the time under test at which fixing additional failures would not provide a significant improvement in the life of the product; and (3) failure mode histogram, which indicates the repeatability of failures in a product. Using techniques like FMVT can provide a means of breaking the tyranny of statistics over durability and reliability testing in a competitive business climate. Copyright © 2004 John Wiley & Sons, Ltd.
Modelling Feasible Design Regions Using Lattice‐based Kernel Methods
Authors: Bates R. A. , Wynn H. P. 
Published: February 2004

AbstractReliability, robustness and general performance are key indicators when attempting to improve the design of existing engineering systems. The search for an improved design is conducted in the space of all possible designs, referred to as the design space. Often when searching this space, infeasible or unsafe regions are encountered, perhaps because particular combinations of parameter values are not physically possible. Such regions need to be avoided during optimization to ensure that any new design is itself feasible. In addition, when considering the reliability and robustness of a design, it may be important to know how far a feasible design is from any boundary. Indeed, it may be the case that such distances are directly related to the reliability and robustness of the design and it may, therefore, be useful to model the boundary between feasible and infeasible regions. This paper proposes the use of Hilbert bases as a method of identifying points in the design space that are close to, or on, the feasible boundary and then uses this information to model the boundary by defining positive definite kernels on new spaces such as hyperspheres. In this way it is possible to model whole surfaces as opposed to single functions. Copyright © 2004 John Wiley & Sons, Ltd.
Reliability Improvement of a Diesel Engine Using the FMETA Approach
Authors: Arcidiacono G. , Campatelli G. 
Published: February 2004

AbstractThis paper provides a way to deal with issues related to design for reliability using axiomatic design (AD). A theoretical approach is studied, starting from the traditional theory of AD, in order to help designers to optimize the product's reliability using a structured approach. The aim of this work is to introduce a new method that is able to assess the product reliability using the support of the AD methodology combined with other methods, e.g. FMEA and FTA. The approach developed is called failure mode and effect tree analysis (FMETA). FMETA allows the designer to find the most critical characteristic of the product from a reliability point of view and provides the designer with a set of possible changes. The core of this work is the development of a reliability tree, used to evaluate both the RPN for the component of the product and to find the reliability relation useful for the following optimization. The reliability tree is born from the combined use of AD, FMEA and FTA. This method has been validated by an application to an automotive heavy‐duty diesel engine. Copyright © 2004 John Wiley & Sons, Ltd.
Electronic structure and molecular orbital study of the first excited state of the high‐efficiency blue OLED material bis(2‐methyl‐8‐quinolinolato)aluminum(III) hydroxide complex from ab initio and TD‐B3LYP
Authors: Gao Hong‐Ze , Su Zhong‐Min , Qin Chun‐Sheng , Mo Ri‐Gen , Kan Yu‐He 
Published: February 2004

AbstractBis(2‐methyl‐8‐quinolinolato)aluminum(III) hydroxide complex (AlMq2OH) is used in organic light‐emitting diodes (OLEDs) as an electron transport material and emitting layer. By means of ab initio Hartree–Fock (HF) and density functional theory (DFT) B3LYP methods, the structure of AlMq2OH was optimized. The frontier molecular orbital characteristics and energy levels of AlMq2OH have been analyzed systematically to study the electronic transition mechanism in AlMq2OH. For comparison and calibration, bis(8‐quinolinolato)aluminum(III) hydroxide complex (Alq2OH) has also been examined with these methods using the same basis sets. The lowest singlet excited state (S1) of AlMq2OH has been studied by the singles configuration interaction (CIS) method and time‐dependent DFT (TD‐DFT) using a hybrid functional, B3‐LYP, and the 6‐31G* basis set. The lowest singlet electronic transition (S0 → S1) of AlMq2OH is π → π* electronic transitions and primarily localized on the different quinolate ligands. The emission of AlMq2OH is due to the electron transitions from a phenoxide donor to a pyridyl acceptor from another quinolate ligand including C → C and O → N transference. Two possible electron transfer pathways are presented, one by carbon, oxygen, and nitrogen atoms and the other via metal cation Al3+. The comparison between the CIS‐optimized excited‐state structure with the HF ground‐state structure indicates that the geometric shift is mainly confined to the one quinolate and these changes can be easily understood in terms of the nodal patterns of the highest occupied and lowest unoccupied molecular orbitals. On the basis of the CIS‐optimized structure of the excited state, TD‐B3‐LYP calculations predict an emission wavelength of 499.78 nm. An absorption wavelength at 380.79 nm on the optimized structure of B3LYP/6‐31G* was predicted. They are comparable to AlMq2OH 485 and 390 nm observed experimentally for photoluminescence and UV‐vis absorption spectra of AlMq2OH solid thin film on quartz, respectively. Lending theoretical corroboration to recent experimental observations and supposition, the reasons for the blue‐shift of AlMq2OH were revealed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
On Ehrenfest's theorem
Authors: Sahni Viraht 
Published: February 2004

AbstractEhrenfest's theorem for a system of electrons in a time‐dependent external force is the quantal analogue to Newton's second law of motion for interacting classical particles. The theorem is in terms of the averaged force and position of the electrons. Here we draw the quantal analogue to the equation of motion for the individual classical particle and thereby describe the internal forces experienced by each electron and the evolution of these forces with time. This explanation is based on the description of Schrödinger theory in terms of fields and their quantal sources. The quantum mechanical average of the internal fields and their averaged torques, taken over all the electrons, vanish as they must. However, unlike classical physics, the vanishing of the averaged internal fields cannot be attributed solely to Newton's third law but is additionally a consequence of quantum mechanics. The field perspective thus leads to a new derivation of Ehrenfest's theorem. Furthermore, the theorem can be expressed in terms of the response of the electrons to the external field as described by a field representative of the electronic current density. In addition, the vanishing of the averaged torque of the internal fields leads to a quantal torque–angular momentum equation analogous to that of classical physics. The structure of the internal fields is demonstrated for both a ground and an excited state of the analytically solvable Hooke's atom. The concept of the internal field is extended via quantal density functional theory to the S system of noninteracting Fermions with density equivalent to that of the Schrödinger theory of electrons. By invoking Ehrenfest's theorem and the quantal torque–angular momentum relationship, sum rules for the S system are derived. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Oxidative polymerization of 5 amino,1,10‐phenanthroline: A theoretical study
Authors: Mora M. A. , Galicia Laura , Mora‐Ramirez M. A. 
Published: February 2004

AbstractThe molecular and electronic structures of 5‐amino‐1,10‐phenanthroline and its monoprotonated and diprotonated species were obtained from ab initio quantum mechanical calculations with unrestricted Hartree–Fock (HF) and Møller–Plesset perturbation theories. The analysis of the net atomic charges and the total spin densities show three possible sites for the monomeric coupling in the polymerization process. The minimal energy conformation for the different kinds of coupling in the formation of the dimers was obtained. The studies were extended to the HF/6‐311 + G(2d,p)//B3LYP (Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Paar)/6‐31G(d) level of theory to obtain theoretical nuclear magnetic resonance spectra to study the number and kinds of species involved in the protonation mechanism. Theoretical and experimental nuclear magnetic resonance spectra are in excellent agreement. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Variational principles for bound states of Schrödinger and Dirac equations allowing the use of discontinuous trial functions
Authors: Szmytkowski Radosław , Bielski Sebastian 
Published: February 2004

AbstractWe present systematic constructions of variational principles for energies of bound states of the Schrödinger and Dirac equations. The principles allow the use of discontinuous trial functions. The method employed is based on a generalized Lagrange procedure. Relationships between our variational principles and those available in the literature are established. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Generalized population analysis of three‐center two‐electron bonding
Authors: Ponec Robert , Cooper David L. 
Published: February 2004

AbstractModern valence bond theory, in its spin‐coupled (SC) form, is used to assess the utility of generalized population analysis, using correlated density matrices, for identifying patterns of three‐center two‐electron bonding in B2H6, B3H, and CH2Li2. The effect on the relevant three‐center indices of including electron correlation, via the SC method, is assessed by means of comparison with analogous Hartree–Fock values. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Impacts of different weed cutting practices on macrophyte species diversity and composition in a Danish stream
Authors: Baattrup‐Pedersen Annette , Riis Tenna 
Published: February 2004

AbstractVarious effects of stream management on biotic communities have been suggested on the basis of observations and investigations in regularly managed streams throughout Europe, but only very sparse information is available about if and how stream management can be combined with maintaining a natural and diverse stream flora. Our study was carried out to investigate how weed cutting practice and frequency can affect macrophyte communities to provide knowledge for future decisions regarding management in streams. We chose an experimental approach and applied four different weed cutting practices (cutting full width, central channel, diagonal channels and no cutting) and frequencies within one stream reach for four years. We found only very limited changes over the four years in overall macrophyte diversity parameters following different management practices and there were no changes in macrophyte diversity parameters either as a function of the weed cutting frequency or method applied. In contrast we found directional changes in macrophyte composition following frequent cuttings of either the whole stream channel or a less comprehensive cutting of only one central channel for four years. In both cases the macrophyte communities changed towards a more Ranunculus dominated community while Potamogeton natans became less important in the community. This change seemed to reflect a higher tolerance of Ranunculus towards disturbance. On the basis of these results, we recommend that the management frequency in streams is limited and, if several cuttings are needed to prevent bank over‐flow, cutting in several narrow channels is preferable to cutting in one central channel as directional changes in plant communities are avoided. Copyright © 2003 John Wiley & Sons, Ltd.
Effect of mixing patterns and light dose on growth of Anabaena circinalis in a turbid, lowland river
Authors: Westwood Karen J. , Ganf George G. 
Published: February 2004

AbstractAnabaena circinalis is common in the lower Murray River, Australia, and may compromise water quality due to the release of toxins. The water is turbid and thermal structure may significantly affect light availability. An in situ experiment was designed to represent complete mixing, diurnal stratification and persistent stratification and test the effect on growth of A. circinalis. To represent the mixing treatments, cells were incubated in diffusion chambers that were adjusted to different positions in the water‐column throughout the day. Populations exposed to persistent stratification over six days grew significantly faster than the other treatments at a rate of 0.65 day−1. However, growth of the diurnally stratified populations was slower than (0.28 day−1), or similar to (0.40 day−1) the mixed population (0.40 day−1). Therefore, the growth of the subpopulations exposed to the euphotic zone was insufficient to counteract the slow growth of the majority that were confined to darkness during the stratified period. A relationship between growth rate (G) and average daily light dose (I) was constructed and growth rate at optimal light dose (Gmax), slope of linear section of G–I curve (α), and light dose where lines of Gmax and light‐limited portion of G–I curve intersect (Ik) were solved as 0.66 day−1, 0.12 day−1 (mol−1 m−2 day−1)−1 and 5.4 mol m−2 day−1, respectively. Using these parameters, a model was developed to predict possible differences in growth between diurnal and mixed populations under varying conditions of vertical light attenuation, mixed depth and incubation time. Copyright © 2003 John Wiley & Sons, Ltd.
A survey of methods for setting minimum instream flow standards in the Caribbean basin
Authors: Scatena F. N. 
Published: February 2004

AbstractTo evaluate the current status of instream flow practices in streams that drain into the Caribbean Basin, a voluntary survey of practising water resource managers was conducted. Responses were received from 70% of the potential continental countries, 100% of the islands in the Greater Antilles, and 56% of all the Caribbean island nations. Respondents identified ‘effluent discharges’, ‘downstream water quality’ and ‘existing extraction permits’ to be the most common sources of instream flow conflicts. In 75% of the countries, some type of ‘formal procedures’ exist for reviewing permit applications for freshwater extraction. In 82% of the countries, effluent discharge permits state the amount of effluent that can be discharged into a water body while only 69% require that surface water extraction permits explicitly state the quantity of water that can be extracted. In setting instream flow requirements, record low flow is used over 83% of the time. Freshwater fish were identified as the most important aquatic organism but no country ‘always’ considers the ecology or habitat requirements of aquatic species in their instream flow determinations and nearly 70% of the respondents indicated that multivariate, ecological‐based methods are ‘never’ used in their country. Survey responses also indicate there is a notable lack of public involvement during the issuing of water permits. Moreover, over 80% of the countries do not provide public announcements or hearings during the permit process. In summary, this survey indicates that while there is a widespread recognition of the need for instream flows, there is a general lack of regionally based information and public involvement regarding stream flow determination. Copyright © 2003 John Wiley & Sons, Ltd.
The importance of inshore areas for adult fish distribution along a free‐flowing section of the Danube, Austria
Authors: Hirzinger V. , Keckeis H. , Nemeschkal H. L. , Schiemer F. 
Published: February 2004

AbstractThis study analyses bank morphological parameters of inshore areas as significant qualifying criteria for the habitat of riverine fish in large rivers. The mesoscaled (1.04±0.35 km) spatial distribution of adult fish was studied along a 50 km stretch of a free‐flowing section of the Austrian Danube. Fish abundance at the inshore zone of the main channel was assessed every month from March 1992 to May 1993, applying stratified random sampling by electrofishing.In order to calculate river morphological variables, a specific DOS application was programmed taking riverbank profiles, slope of the Danube and mean daily water level into account. The sampling sites by environmental variables were analysed by principal component analysis (PCA). PCA scores, together with the relative densities of each fish species in terms of their proportions per catch, were treated by a simple logistic regression. The different species exhibit specific patterns of statistical probability in terms of distribution and densities at distinct structural inshore types with regard to area, slope, habitat heterogeneity and connectivity parameters.Large gradually sloping inshore areas are characterized by rheophilic Chondrostoma nasus, Leuciscus idus and Abramis ballerus, whereas eurytopic species do not show a consistent pattern. Heterogeneous stretches contain high proportions of Leuciscus cephalus, Abramis brama and Abramis ballerus. Connectivity discriminates strictly riverine species like Chondrostoma nasus from rheophilic species which require non‐channel habitat during their life history. Copyright © 2003 John Wiley & Sons, Ltd.
Patterns of channel adjustment to impoundment of the upper River Spey, Scotland (1942–2000)
Authors: Gilvear David J. 
Published: February 2004

AbstractOver the last 30 years, understanding of how river channel morphology adjusts to upstream impoundment has been improved considerably with clearwater erosion close to the dam and aggradation downstream of unregulated tributary confluences being identified. In a UK context our understanding of channel response to impoundment has been based principally on analysis of a number of regulated rivers using a time–space substitution approach but the temporal pattern of channel change was not fully observed. This paper details channel change over almost six decades following impoundment of the River Spey, Scotland, primarily via the use of cartographic and aerial photographic evidence. Channel change initially involved the formation of tributary confluence bars followed by bench development and vegetation colonization and development on the benches and gravel bars. Sixty years after impoundment, the channel is still adjusting its form at distance from the dam to be in quasi‐ equilibrium with its regulated flow regime; indeed adjustment was most rapid between 1989 to 1995. This accelerated adjustment is due to the occurrence of a greater number of large and geomorphologically significant flood events in this period. Sediment supply limitation from unregulated tributaries will have stemmed the rate of narrowing and bench development prior to 1989. This spatial and temporal pattern of adjustment supports, for the most part, the model advocated by Petts (Progress in Physical Geography, 1979, Vol. 3, pp. 329–362). The wider implications of the channel change for river conservation and management are addressed. Copyright © 2003 John Wiley & Sons, Ltd.
Prospects for developing absorptive capacity through internal information provision
Authors: Lenox Michael , King Andrew 
Published: February 2004

AbstractTheories of absorptive capacity propose that knowledge gained from prior experience facilitates the identification, selection, and implementation of related profitable practices. Researchers have investigated how managers may develop absorptive capacity by building internal knowledge stocks, but few have focused on the distribution of this knowledge within the firm and the role managers play in administering information to organizational subunits. In this paper, we explore the degree to which managers can develop absorptive capacity by directly providing information to agents in the organization that might potentially adopt a new practice. We find that the effectiveness of managerial information provision depends on the degree to which potential adopters have information from other sources. We find that information from previous adopters and past events reduces the effect of information provision, while experience with related practices amplifies it. Our research helps clarify when absorptive capacity may provide a sustained competitive advantage. Copyright © 2004 John Wiley & Sons, Ltd.
Emergent patterns of strategy, environment and performance in a transition economy
Authors: Davies Howard , Walters Peter 
Published: February 2004

AbstractInsights from the resource dependence approach, dynamic fit, and strategic choice theories are used to explore the strategies adopted by Chinese enterprises, their settings, and the relationship between strategy, environment, and performance. Results from 959 firms indicate that respondents operating under ‘more marketized’ institutional settings tend to locate themselves in more munificent environments and place greater emphasis on meeting customer needs. Firms in China do not trade off one strategic direction against another, and certain strategy/environment coalignments have significant implications for performance. In particular, performance is better in more marketized and munificent environments and amongst firms who adopt an ‘aggressive’ strategic posture. Copyright © 2004 John Wiley & Sons, Ltd.