Linear Functional Relationship Research Articles

Amostragem e agrupamento de dados de relação hipsométrica em inventários florestais de Cerrado Tocantinense

<p class="Resumo">Este estudo foi conduzido com o objetivo de avaliar o emprego de equações hipsométricas em cerrado <em>sensu stricto</em> focalizando o sistema de amostragem e o agrupamento dos dados de relação hipsométrica. Para isso, foram utilizadas 46 parcelas de 1.000 m² cada, onde 13 parcelas foram empregadas na simulação de seis diferentes sistemas de amostragem e na estratificação de dados para o ajuste de modelos hipsométricos. As 33 parcelas restantes foram reservadas para um teste de aplicação das equações hipsométricas geradas, onde, para decidir quanto ao modelo hipsométrico e sistema de amostragem, foram adotados os critérios estatísticos: erro padrão residual e correlação linear múltipla, além da análise da distribuição de resíduos. Após esta decisão, foi utilizado um teste de identidade de modelos para verificar a melhor forma de preparar a base de dados visando o ajuste de modelos hipsométricos. Concluiu-se que a relação funcional linear: Ln(h)=f[Ln(N); Ln(dq/d); 1/d] foi a mais adequada para caracterizar a relação hipsométrica em inventários florestais de cerrado sensu stricto e deve ser ajustada com dados obtidos nas 50 primeiras árvores de cada parcela, sem agrupamento por classe de diâmetro.</p>

Rational quantum integrable systems of [formula omitted] type with polarized spin reversal operators

We study the spin Calogero model of DN type with polarized spin reversal operators, as well as its associated spin chain of Haldane–Shastry type, both in the antiferromagnetic and ferromagnetic cases. We compute the spectrum and the partition function of the former model in closed form, from which we derive an exact formula for the chain's partition function in terms of products of partition functions of Polychronakos–Frahm spin chains of type A. Using a recursion relation for the latter partition functions that we derive in the paper, we are able to numerically evaluate the partition function, and thus the spectrum, of the DN-type spin chain for relatively high values of the number of spins N. We analyze several global properties of the chain's spectrum, such as the asymptotic level density, the distribution of consecutive spacings of the unfolded spectrum, and the average degeneracy. In particular, our results suggest that this chain is invariant under a suitable Yangian group, and that its spectrum coincides with that of a Yangian-invariant vertex model with linear energy function and dispersion relation.

Bayesian nonlinear model selection for gene regulatory networks.

Gene regulatory networks represent the regulatory relationships between genes and their products and are important for exploring and defining the underlying biological processes of cellular systems. We develop a novel framework to recover the structure of nonlinear gene regulatory networks using semiparametric spline-based directed acyclic graphical models. Our use of splines allows the model to have both flexibility in capturing nonlinear dependencies as well as control of overfitting via shrinkage, using mixed model representations of penalized splines. We propose a novel discrete mixture prior on the smoothing parameter of the splines that allows for simultaneous selection of both linear and nonlinear functional relationships as well as inducing sparsity in the edge selection. Using simulation studies, we demonstrate the superior performance of our methods in comparison with several existing approaches in terms of network reconstruction and functional selection. We apply our methods to a gene expression dataset in glioblastoma multiforme, which reveals several interesting and biologically relevant nonlinear relationships.

Predicting bobcat abundance at a landscape scale and evaluating occupancy as a density index in central Wisconsin

The abundance of low-density species like carnivores is logistically difficult to directly estimate at a meaningful scale. Predictive distribution models are often used as a surrogate for density estimation. But because density can continue to increase as occupancy asymptotes at 1, occupancy may have little value as an index, and home range expansion in marginal habitat may further confound the association. We sought to estimate bobcat population size at a landscape scale (14,286 km2) in central Wisconsin, which provided an opportunity to relate predicted occurrence to individual space use and population density. We sampled bobcats using motion-sensitive trail cameras at 9 arrays across central Wisconsin. We estimated bobcat site-specific occupancy, and regressed these estimates as linear or asymptotic functions of site-specific density to determine the strength and shape of their association. We subsequently modeled both parameters relative to habitat covariates and repeated the regression process. A linear functional relationship between density and occupancy was most supported when detection parameters were held constant (wi= 0.97, R2 = 0.72) and when detection, occurrence, and density were modeled as a function of habitat covariates (wi= 0.99, R2 = 0.95). This suggests that repeated presence-absence data alone may be an efficient and reliable method for inferring spatial patterns in bobcat density or identifying habitat types with greater density potential in the northern parts of its range. Bobcat occupancy and density were both positively associated with surrounding woody cover and wetland edge density. Our most supported spatially explicit capture-recapture model estimated bobcat abundance as 362 adult individuals (95% CI 272–490) across the study area. © 2015 The Wildlife Society.

Effect of a DC Field on Temperature Distribution in a Thin FGM Metal Line Subjected to Distributed Local Heating Sources

The effect of a direct-current field on the temperature distribution in a thin, non-uniform functionally graded metal line subjected to distributed local heat sources is investigated. The material properties of the metal line are assumed to vary over the span following a linear functional relationship. Bump-like heat sources of different profiles are considered to simulate the condition of distributed local heating of the metal line. The governing differential equations associated with the electrical and thermal problems are derived in terms of variable thermal and electrical conductivity of the material. The solution of the coupled boundary-value problem is then obtained using a finite-difference computational scheme. The temperature distributions in the FGM line are determined for different environmental conditions as a function of intensity of the DC field.

A robust method to estimate the variation of the vortex shedding frequency with the location of a single spanwise tripwire for circular cylinders in subcritical flow

For circular cylinders fitted with a single spanwise tripwire, this paper develops a mathematical estimation method to predict the variation of the vortex shedding frequency (in the form of Strouhal number (St)) with the tripwire location (θ) for a given Reynolds number (ReD) and tripwire size (d). The basis of this method comes from the experimentally-determined data of vortex shedding frequency through Constant Temperature Anemometry (CTA) measurements. During the course of these measurements, the Reynolds number is changed from ReD=5000 to 30,000, the tripwire size is varied in diameter from 2.9% to 5.9% of the cylinder diameter and the tripwire location on the cylinder surface is changed from θ=0° to 180° with respect to the forward stagnation point of the cylinder.The estimation method proposed in this study requires only the wire diameter (d), the cylinder diameter (D) and the Reynolds number (ReD) as the input variables. In the first step, the ratio of the wire size to the unperturbed boundary layer thickness is determined at a selected circumferential location on the cylinder. This non-dimensional parameter is, then, used to predict the critical wire angles, and the minimum and maximum values of St according to an experimentally determined linear functional relationship. In the second step, the similarity of the St–θ curves at different wire sizes and Reynolds numbers permits the transformation of the St–θ data to a new modified domain (called St⁎–θ⁎), which yields a universally valid quantitative relationship for any wire size and Reynolds number considered. Using this modified functional relationship in conjunction with the predicted critical wire angles and Strouhal number boundaries, the St–θ curves are constructed. Estimated St values using this method show a reasonably good agreement with the experimental data acquired in the current study.

A drift correction optimization technique for the reduction of the inter-measurement dispersion of isotope ratios measured using a multi-collector plasma mass spectrometer

The effects of polynomial interpolation and internal standardization drift corrections on the inter-measurement dispersion (statistical) of isotope ratios measured with a multi-collector plasma mass spectrometer were investigated using the (analyte, internal standard) isotope systems of (Ni, Cu), (Cu, Ni), (Zn, Cu), (Zn, Ga), (Sm, Eu), (Hf, Re) and (Pb, Tl). The performance of five different correction factors was compared using a (statistical) range based merit function ωm which measures the accuracy and inter-measurement range of the instrument calibration. The frequency distribution of optimal correction factors over two hundred data sets uniformly favored three particular correction factors while the remaining two correction factors accounted for a small but still significant contribution to the reduction of the inter-measurement dispersion.Application of the merit function is demonstrated using the detection of Cu and Ni isotopic fractionation in laboratory and geologic-scale chemical reactor systems. Solvent extraction (diphenylthiocarbazone (Cu, Pb) and dimethylglyoxime (Ni)) was used to either isotopically fractionate the metal during extraction using the method of competition or to isolate the Cu and Ni from the sample (sulfides and associated silicates). In the best case, differences in isotopic composition of ±3 in the fifth significant figure could be routinely and reliably detected for Cu65/63 and Ni61/62.One of the internal standardization drift correction factors uses a least squares estimator to obtain a linear functional relationship between the measured analyte and internal standard isotope ratios. Graphical analysis demonstrates that the points on these graphs are defined by highly non-linear parametric curves and not two linearly correlated quantities which is the usual interpretation of these graphs. The success of this particular internal standardization correction factor was found in some cases to be due to a fortuitous, scale dependent, parametric curve effect.

Classification of Structural Complexity for Mine Ventilation Networks

The mine ventilation system is most important and technical measure for ensuring safety production in mines. The structural complexity of a mine ventilation network can directly affect the safety and reliability of the underground mining system. Quantitatively justifying the degree of complexity can contribute to providing a deeper understanding of the essential characteristics of a network. However, so far, there is no such a model which is able to simply, practically, reasonably, and quantitatively determine or compare the structural complexity of different ventilation networks. In this article, by analyzing some typical parameters of a mine ventilation network, we conclude that there is a linear functional relationship among five key parameters (number of ventilation network branches, number of nodes, number of independent circuits, number of independent paths, and number of diagonal branches). Correlation analyses for the main parameters of ventilation networks are conducted based on SPSS. Based on these findings, a new evaluation model for the structural complexity of ventilation network (which is represented by C) has been proposed. By combining SPSS classification analyses results with the characteristics of mine ventilation networks, standards for the complexity classification of mine ventilation systems are put forward. Using the developed model, we carried out analyses and comparisons for the structural complexity of ventilation networks for typical mines. Case demonstrations show that the classification results correspond to the actual situations. © 2014 Wiley Periodicals, Inc. Complexity 21: 21–34, 2015

Designing for emotional satisfaction: an inquiry of passengers' subjective experience on assistive products for train travel

This study examines how a manner of use of a product can influence a travelers' subjective experience during the peak passenger traffic season in mainland China. A survey has been utilized to conduct empirical studies on passenger's emotional satisfaction. Qualitative methods are adopted to analyze subjective experience, and emotional satisfaction of passengers on the trains. The analysis is based on responses collected via an online sample survey questionnaire and field questionnaire at Wuchang railway station to investigate the emotional descriptions of train travel experience. The results indicated that passenger's experienced better emotional satisfaction after they utilized a travel-assistive product on the train carriage. As well, negative emotions are found in semantic descriptions of passengers through questionnaires, field observations, and direct interviews. These findings suggest that passengers' subjective experience is a linear functional relation, and the manner of use of a creative product may provide possible solutions to improve a passengers' subjective experience. The results provided a view on the negative emotions of subjective experience that were the foremost influencing factor on emotional satisfaction. These represent the source for creativity and innovation with respect to train design. The study also showed there is a huge market for the design of travel-assistive products that serve travelers, and a challenge and opportunity for designers to improve its possible social effects.

A novel physics-based temperature compensation model for structural health monitoring using ultrasonic guided waves

This article investigates the role of ambient temperature in causing changes to the structural wave propagation, as sensed by piezoelectric transducers, in a newer perspective. A novel approach is proposed to compensate the influence of temperature on piezo-sensor response using both analytical models and numerical simulations. Parametric studies using numerical simulations for plates with surface-mounted piezoelectric transducers establish linear functional relationship between change in sensor signals and specific combination of material properties, within certain temperature range. A numerical temperature compensation model is developed based on this functional relationship to reconstruct piezo-sensor signals at elevated temperatures. Matching pursuit–based signal analysis and reconstruction schemes are used in this study. Practical efficacy of the compensation model is tested for metallic structures with both simple and complex geometries. Model-based reconstruction of first wave packets in the sensor signals is found to match quite well with the experimental measurements. Performance of the proposed compensation model is also found to be at par with the existing state-of-art temperature compensation methods. A very limited set of baseline sensor data is required to estimate unknown model parameters, making this approach to be efficient and practically useful. The output of the compensation model is also used to obtain an accurate estimate of damage location in a structure under varying ambient temperature environments.

Nonlinear energy transfers and phase diagrams for geostrophically balanced rotating-stratified flows.

Equilibrium statistical mechanics tools have been developed to obtain indications about the natural tendencies of nonlinear energy transfers in two-dimensional and quasi-two-dimensional flows like rotating and stratified flows in geostrophic balance. In this article we consider a simple model of such flows with a nontrivial vertical structure, namely, two-layer quasigeostrophic flows, which remain amenable to analytical study. We obtain the statistical equilibria of the system in the case of a linear vorticity-stream function relation, build the corresponding phase diagram, and discuss the most probable outcome of nonlinear energy transfers, both on the horizontal and on the vertical, in the presence of stratification and rotation.

Chaotic magnetic fields in Vlasov-Maxwell equilibria

Stationary solutions of Vlasov-Maxwell equations are obtained by exploiting the invariants of single particle motion leading to linear or nonlinear functional relations between current and vector potential. For a specific combination of invariants, it is shown that Vlasov-Maxwell equilibria have an associated Hamiltonian that exhibits chaos.

Hysteresis between coral reef calcification and the seawater aragonite saturation state

AbstractSome predictions of how ocean acidification (OA) will affect coral reefs assume a linear functional relationship between the ambient seawater aragonite saturation state (Ωa) and net ecosystem calcification (NEC). We quantified NEC in a healthy coral reef lagoon in the Great Barrier Reef during different times of the day. Our observations revealed a diel hysteresis pattern in the NEC versus Ωa relationship, with peak NEC rates occurring before the Ωa peak and relatively steady nighttime NEC in spite of variable Ωa. Net ecosystem production had stronger correlations with NEC than light, temperature, nutrients, pH, and Ωa. The observed hysteresis may represent an overlooked challenge for predicting the effects of OA on coral reefs. If widespread, the hysteresis could prevent the use of a linear extrapolation to determine critical Ωa threshold levels required to shift coral reefs from a net calcifying to a net dissolving state.

A Variable Step Size LMS Adaptive Filtering Algorithm and Simulations Based on Computational Verb Theory

Based on traditional LMS algorithm, variable step LMS algorithm and the analysis for improved algorithm, a new variable step adaptive algorithm based on computational verb theory is put forward. A kind of sectorial linear functional relationship is established between step parameters and the error. The simulation results show that the algorithm has the advantage of slow change which is closely to zero. And overcome the defects of some variable step size LMS algorithm in adaptive steady state value is too large.

Influence of Deformation and Quenching Temperature on Structures and Properties of High Nitrogen Stainless Bearing Steel

The influence of deformation and quenching temperature on microstructure and properties for high nitrogen stainless bearing steel was studied using the calculation of Thermo-Calc software and relevant Fe-based database and some experiments. The results showed that there was a small precipitation amount of carbide in the sample after a large deformation. The value of impact toughness (AKU) was increased from 2.0 J to 12.0 J with the deformation increasing from 71% to 83%. When the quenching temperature reached 1050, the value of the hardness was up to the tiptop. Additionally, according to the calculation, it was found that there was a linear functional relation between the precipitation of carbide M23C6(M) and quenching temperature (T). And the relational model could be expressed as:MM23C6=55.34 - 0.05T(T1000).

P_MOEA:一种多目标决策辅助遗传算法用于服务组合QoS优化

For the QoS management of service composition, one of the most important problems is how to find the optimal solutions for the service composition under certain SLA constraints. There are two main challenges existing for this optimization problem of SLA constraint service composition. At first, since many QoS dimensions are involved to describe the qualities of service composition, it is a typical multi-criteria decision making problem, where effective ranking model is required to rank candidate solutions and to identify optimal solutions. On the other hand, it is also a combinatorial optimization problem that is NP-hard, where the efficient and scalable algorithm is necessary for finding optimal solutions from large scale service composition candidates. In most traditional approaches, two kinds of techniques have been used to define the optimal solutions for service composition, i.e. the linear utility function and Pareto dominance relation. In the former, precise numeric weights are required for the definition of utility function, which is a hard task for users especially when the number of QoS dimensions increase. In the latter, weights assignments are not necessary and a set of skyline solutions are identified as optimal results. However, the scale of results set is uncontrollable, when the problem scale increases the number of skyline solutions will become too many to provide any insights for users to make the final selection. To cope with these drawbacks of traditional methods, in this paper we firstly introduce the PROMETHEE model into this challenging optimization problem. By combining it with Pareto optimization, we redefine optimization objective as top-k PROMETHEE optimal solutions based on skyline computation. Then, we present an efficient evolutionary algorithm: P_MOEA, which can efficiently find the Top-k optimal solutions for large scale service composition problem. We evaluate the effectiveness, efficiency and scalability of our approach with comprehensive analytical and experimental study.

The Monitoring of Linear Profiles with a GLR Control Chart

In this paper, we consider the problem of monitoring a linear functional relationship between a response variable and one or more explanatory variables (a linear profile). The design and application of a generalized likelihood ratio (GLR) control chart are discussed. The likelihood ratio test of the GLR chart is generalized over the regression coefficients, the variance of the error term, and the possible change point. The performance of the GLR chart is compared with various existing control charts. We show that the overall performance of the GLR chart is much better than other options in detecting a wide range of shift sizes. The existing control charts designed for certain shifts that may be of particular interest have several chart parameters that need to be specified by the user, which makes the design of such control charts more difficult. The GLR chart is very simple to design, as it is invariant to the choice of design matrix and the values of in-control parameters. Therefore, there is only one design parameter (the control limit) that needs to be specified. Another advantage of the GLR chart is its built-in diagnostic aids that provide estimates of both the change point and the values of linear profile parameters.

A field experiment on dust emission by wind erosion in the Taklimakan Desert

Dust emission by wind erosion in surface is a serious problem in many arid regions around the world, and it is harmful to the ecological environment, human health, and social economy. To monitor the characteristics of saltation activity and to calculate the threshold wind velocity and sediment discharge under field conditions have significance on the research of dust emission by wind erosion. Therefore, a field experiment was conducted over the flat sand in the hinterland of the Taklimakan Desert. One sampling system was installed on the flat sand surface at Tazhong, consisting of a meteorological tower with a height of 2 m, a piezoelectric saltation sensor (Sensit), and a Big Spring Number Eight (BSNE) sampler station. Occurrence of saltation activity was recorded every second using the Sensit. Each BSNE station consisted of five BSNE samplers with the lowest sampler at 0.05 m and the highest sampler at 1.0 m above the soil surface. Sediment was collected from the samplers every 24 h. It is found that saltation activity was detected for only 21.5% of the hours measured, and the longest period of saltation activity occurring continuously was not longer than 5 min under the field conditions. The threshold wind velocity was variable, its minimum value was 4.9 m s−1, the maximum value was 9.2 m s−1, and the average value was 7.0 m s−1. The threshold wind velocity presented a positive linear increase during the measurement period. The observation site had a sediment discharge of 82.1 kg m−1 over a period of 24 h. Based on hourly saltation counts, hourly sediment discharge was estimated. Overall, there was no obvious linear or other functional relationship between the hourly sediment discharge and wind velocity. The results show that the changes of sediment discharge do not quite depend on wind velocity.

Embedded Software Energy Modeling Method at Architecture Level

从软件体系结构层面出发,假设体系结构级软件特征量与嵌入式软件能耗之间存在非线性函数关系(线性函数关系可被认为是一种特殊的非线性函数关系),并以此假设为基础,提出了一种利用BP神经网络在体系结构级估算软件能耗的模型.能耗模型对5个体系结构级软件特征量进行度量,使用BP神经网络拟合出软件特征量与嵌入式软件能耗的非线性函数关系,并通过实验验证了模型的有效性和假设的合理性.;This paper starts at a software architecture level, considers the functional relation between software characteristic quantities and embedded software energy as nonlinear (linear functional relation can be considered as a special nonlinear functional relation). Next, the paper presents an energy model at architecture level by using BP neural network. The energy model measures 5 software characteristic quantities at architecture level and uses BP neural network to fit the functional relation between software characteristic quantities and embedded software energy. Experimental results show that this model is effective.

Vlasov-Maxwell equilibria: Examples from higher-curl Beltrami magnetic fields

Stationary solutions of Vlasov-Maxwell equations are obtained by exploiting the invariants of single particle motion and lead to linear or nonlinear functional relations between current and vector potential. The nonlinear relations support various special types of magnetic configurations including multiple current sheets and magnetic field discontinuities leading to singular current layers. It is demonstrated through the examples that in one dimension, the description of the equilibrium magnetic fields obeys double or higher-curl Beltrami equation. For the linear case, such representation gives the advantage of obtaining exact analytic solutions that are expressed as a superposition of the single-curl Beltrami fields.