Norm optimization techniques for improved structural reanalysis

Digital building data models are increasingly employed in the design and construction planning of buildings, so that almost the entire planning process is covered with three‐dimensional (3D) models. Starting with available detailed CAD data it is easy to generate 3D models for the design analysis. However, this comes with a price since the complexity of the 3D models requires a high computational effort. Considering the fact that the structural engineer often must investigate numerous design variants and system modifications during the planning stage to reach an optimal solution it makes sense to facilitate the multitude of these recalculations by an easy‐to‐use reanalysis technique.The approximation method we use for reanalysis is referred to as the Sensitivity Analysis with Green's functions (SAGF). The basic principles of the SAGF method can be found in [2,3]. It can be used very advantageously for reanalysis purposes, especially in the presence of complex computational models, and allows for a quick comparison of different design variants. In this paper, the method is used to determine how the system responses (internal forces, displacements) are affected by local changes in the stiffness of frame elements as they are typical for modifications of cross‐sectional values in steel structures such as when haunches are added at nodes.In [1] Abdank already presented an approach to determine the changes in structural response of beams from the subsequent consideration of haunches without performing a complete recalculation. In comparison to this, the presented SAGF method is applied very beneficially in connection with 3D models.Furthermore a 2D implementation of the presented reanalysis technique can be found in the program BE‐FRAMES [4]. It allows for a fast and simple “one‐click”‐reanalysis of various design variants since the designer can traverse the different designs forward and backwards – in a blink of an eye, with simple mouse clicks. An additional benefit is that the program can display influence functions for any displacement and force component so that with this graphical tool the engineer can predict the effects of design changes quite easily.

We introduce a new flexible distribution four-parameter which is called [0,1]Truncated Exponentiated Exponential Burr type X distribution ([0,1] TEE-BX). Using binomial series expansion and exponential expansion, the new distribution is expanded by four parameters. We derive moments, moment generating function, quantile function, order statistics and the Rényi entropy. The maximum likelihood estimation method is used to estimate the parameters of the proposed TEE-BX model [0,1]. Finally, using two real-world data sets, the performance of the [0,1] TEE-BX distribution is explored. Based on the certain goodness of fit criteria, we conclude that the [0,1] TEE-BX distribution has a better fit than the other distributions.

An effective scaling frequency factor method for scaling of harmonic vibrational frequencies: The use of redundant primitive coordinates

An effective scaling frequency factor method for scaling of harmonic vibrational frequencies: theory and preliminary application to toluene

An effective scaling frequency factor method for harmonic vibrational frequencies: The factors’ transferability problem

A lumped-parameter model is considered for open-channel networks that expresses the dynamic relationship, in terms of state space variables, between gate opening sections and stored water volume variations in the different canal reaches with respect to a reference configuration of uniform flow. A procedure is suggested to approximate a real steady flow condition with an ideal uniform flow configuration. A decentralized control is obtained by determining the state feedback gain matrix, whose structure is imposed to be diagonal, that minimizes the H/sub 2/ norm of a suitable transfer matrix. A numerical validation of the linear model used to synthesize the control law is proposed. A comparison between the behaviour of the linear model and that of the non-linear unsteady one, whose evolution has been determined using the SIC software, is proposed.

It is shown that the spectral norm of the closed-loop system matrix is minimized if a special type of minimum variance control is applied. Furthermore, a sufficient condition is derived for the existence of a controller which, with less control effort than this minimum variance controller, obtains the same minimal closed-loop norm.

SummaryLandscape‐ and community‐level CO2 measurements were made at a subarctic sedge fen near Churchill Manitoba during the 1997 growing season. Climatic conditions were warmer and drier than the 30‐y normal. Landscape‐scale micrometeorological measurements indicated that the wetland gained 49 g CO2 m−2 during the growing season. Chamber‐scale measurements from the main vegetation community types showed that small hummocks (Carex spp. sites) dominated the CO2 exchange, yielding an effective scaling factor of 70%. Scaled parameters of two algorithms describing photosynthesis and respiration for each community type show strong similarity to those derived at the landscape level. Scaling photosynthesis, respiration, and net ecosystem CO2 exchange from the community to landscape‐level over the season is within the maximum probable error of each methodological approach and helps substantiate the 1997 CO2 budget. We explore the equilibrium response of net ecosystem CO2 exchange of this fen to climatic change by examining the feedback of water table position on vegetation distribution and nitrogen availability. Based on the effective scaling factors computed for each community type, we hypothesize that a small decrease in mean water table position could nearly triple the net uptake of CO2 at this wetland.

In the predicting process of climate change, accurate assessments require the use of downscaling methods to estimate the parameters of precipitation characteristics. Among the current methods of statistical downscaling, two-point and four-point methods on conditional transition probabilities and the approximation method on daily precipitation variance have led to widespread adoption in various studies around the world because of their straightforwardness, convenience, and practicability. However, two-point and four-point methods underestimated the probability of wet days following wet days in arid and semiarid region, and the approximation method has something in overestimation on daily precipitation variance. Building upon previous works, this study introduced the weighting method on conditional transition probability and the regression method on daily precipitation variance to develop a modified approach. All methods were validated using 100-yr daily precipitation data from Tucson (U.S.) and 60-yr precipitation data from five stations in China. Results showed that all three methods demonstrated strong performance in estimating conditional transition probabilities. The weighting method reduced the biases in the semiarid region. The approximation method exhibited errors in estimating the daily precipitation variance indicated by the negative model efficiency (ME) of self-test in both semiarid and humid regions, while the regression method showed a strong relationship between daily and monthly precipitation variance with high ME of self-test. High ME of validation tests demonstrated that the regression method is highly applicable in both climatic regions. All the results implicated that the weighting method and the regression method introduced in this paper enhance the accuracy of estimation and can be utilized not only in the humid region but also in the semiarid region.

An approximate algorithm for the reanalysis of structures by the finite element method

Traditionally, ERM (Equivalent Random Method) is used to determine number of circuits in an overflow circuit group with rough traffic which has vmr(variance to mean ratio) greater than one. Recently, IPP(Interrupted Poisson Process) approximate method which represents the collective feature of the overflow has been introduced. The negative binomial loss formula can be applied to determine the required number of circuits in the overflow circuit group. In this paper, we deal with the negative binomial loss formula and determination method of number of circuits. We also analyze and compare these three loss formulas.

This article explores the communication model and nature of change in terms of deforestation in China since 1949. Through Lasswell's communication model and the theory of change and via historical analysis and extended literature review, we have discovered: First, Mao's government adopted an effective one-way top-down communication model with Chinese characteristics during 1949 and 1978, which facilitated deforestation in China leading to massive economic dislocation and immense waste of resources. Second, the Chinese government's change to practical ideology brought about new administrative practices of enacting forest protection laws and reorientating the relevant workforces to use available technologies for the production of exported furniture with imported timber. Finally, the paradigmatic shift in the Chinese forest management has partially relocated deforestation from China to other countries, which calls for urgent international attention.

Application of effective stress intensity factor crack closure model to evaluate train load sequence effects on crack growth rates

RTL-based high level design methodology suffers a major drawback in the area of testability analysis due to lack of effective RTL fault models. Testability of a design is considered structure dependent. Since the structure of a design changes drastically with every logic synthesis run, testability analysis is performed only after final logic synthesis and therefore findings of such effort are too late to be implemented in the design without a significant schedule impact. In this paper we analyze the testability relationship between the RT level design and different structural (gate level) implementations resulting from optimization driven logic synthesis runs. We empirically establish that the testability properties of structural implementations are derived from architectural descriptions at the RT level and therefore logic synthesis does not significantly impact them. Furthermore, various different structural implementations resulting from logic synthesis (with different optimization constraints) exhibit poor testability in the same RTL design space. The data presented in this paper provides a missing key ingredient towards successful RTL fault modeling. We also propose the use of preliminary gate level netlist for early analysis to estimate testability properties of the final implementation.

An enhanced frequency dependent subtraction algorithm for removal of cardiac interference from fMEG by using minimum norm projection operator