1,590 research outputs found

    First-Order Decomposition Trees

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    Lifting attempts to speed up probabilistic inference by exploiting symmetries in the model. Exact lifted inference methods, like their propositional counterparts, work by recursively decomposing the model and the problem. In the propositional case, there exist formal structures, such as decomposition trees (dtrees), that represent such a decomposition and allow us to determine the complexity of inference a priori. However, there is currently no equivalent structure nor analogous complexity results for lifted inference. In this paper, we introduce FO-dtrees, which upgrade propositional dtrees to the first-order level. We show how these trees can characterize a lifted inference solution for a probabilistic logical model (in terms of a sequence of lifted operations), and make a theoretical analysis of the complexity of lifted inference in terms of the novel notion of lifted width for the tree

    Nonlinear Model Updating in Structural Dynamics

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    Identification of nonlinear structural dynamics has received a significant attention during last decades. Yet, there are many aspects of the identification methods of nonlinear structural models to be improved. The main objective of this study is to introduce novel identification approaches for nonlinear structures. The first step in identifying nonlinear structural elements is to detect their exact location. Hence, the first section of this study focuses on the localization of nonlinear elements in structural dynamics utilizing base excitation measured data. To this end, a localization approach is used to find the location of nonlinear electromagnetic restoring force applied to the tip of a cantilever beam.Inferring the exact location of nonlinear elements, identification methods are utilized to identify and characterize the mathematical model of nonlinear structures. However, various sources of noise and error may affect the accuracy of the identified model. Therefore, in the second part of the thesis, the effect of various sources of inaccuracy on the results of nonlinear model identification is investigated. It is shown that measurement noise, expansion error, modelling error, and neglecting the effect of higher harmonics may lead to an erroneously identified model.An optimization-based framework for the identification of nonlinear systems is proposed in this work in order to avoid the bottlenecks mentioned above. The introduced method is applied to a test rig composed of a base-excited cantilever beam subjected to an electromagnetic force at the tip. According to the nonlinear response of the system, four different functions are assumed as candidate models for the unknown nonlinear electromagnetic force. The measured response is compared with the reconstructed response using various models and the most appropriate mathematical model is selected.Utilizing optimization-based identification method to characterize complex mathematical models with large number of unknown parameters would be computationally expensive. Therefore, this study introduces a harmonic-balance-based parameter estimation method for the identification of nonlinear structures in the presence of multi-harmonic response and force. For this purpose, a method with two different approaches are introduced: Analytical Harmonic-Balance-based (AHB) approach and the Alternating Frequency/Time approach using Harmonic Balance (AFTHB). The method is applied to five simulated examples of nonlinear systems to highlight different features of the method. The method can be applied to all forms of both smooth and non-smooth nonlinear functions. The computational cost is relatively low since a dictionary of candidate basis functions is avoided. The results illustrate that neglecting higher harmonics, particularly in systems with multi-harmonic response and force, may lead to an inaccurate identified model. The AFTHB approach benefits from including significant harmonics of the response and force. Applying this method leads to accurate algebraic equations for each harmonic, including the effect of higher harmonics without truncated error. In the last part of this study, the AFTHB method is applied to two experimental case studies and identifies the nonlinear mathematical model of the structures. The first case is composed of a cantilever beam with a nonlinear electromagnetic restoring force applied to the tip which is excited by a multi-harmonic external force. In the second experimental case study, a configuration of linear springs applies a geometric nonlinear restoring force to the tip of a cantilever beam resulting in internal resonance in the dynamics of the system. The good performance of the AFTHB approach in estimating the unknown parameters of the structure is illustrated by the results of identification

    LAKI VERBAL INFLECTION

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    This thesis mainly examines inflectional morphology of verbal paradigms in Laki, which is considered as one of the Southern varieties of Kurdish language. The association of form and content of morphological markings are viewed from a realizational angle, in which exponents (morphological forms) are associated with the morphosyntactic properties via the application of rules of exponence, appealed by paradigm functions (Stump 2001) and ordered into rule blocks (Anderson 1992). In particular, I applied the paradigm linkage theory proposed and fully developed by Stump (2002 and 2016) to account for Laki verbal paradigms. In this study, it is claimed that alignment pattern and the syntagmatic combination of some of the inflectional exponents such as agreement markers are sensitive to preterite property. Hence, I argue in favor of considering two distinct morphotactic patternings in Laki. As the result of this assumption, depending on whether the inflectional markers attach to a preterite or a non-preterite stem, we should define two separate sets of affix position in this language. Moreover, I examine Laki polyfunctional agreement markers through the consideration of the morphotactics of this language. Applying Stump\u27s analysis (to appear) of Swahili verbal concords, I consider two distinct types of content for these agreement markers: intrinsic content, and positional content. Their positional content is what the morphotactics of the language determines

    Geology and mineralogy of advanced argillic alteration in the Keshe area (Mt. Karkas), Central Iran

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    Abstract The Keshe area is a part of Cenozoic magmatic belt of Central Iran. Some volcanics in this area underwent hydrothermal alteration including kaolinitization and alunitization. The altered rocks are characterized by an assemblage of alunite, kaolinite and quartz, which is typical in advanced argillic alteration. The mineralogical study suggests that the hydrothermal alteration in this area occurred in a magmatic hydrothermal environment

    Prevalence and genetic characterization of Cryptosporidium spp. In diarrheic children from Gonbad Kavoos city, Iran

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    Background: Cryptosporidium is an intestinal protozean parasite causing water-borne and foodborne outbreaks of diarrheal diseases. The present study was per-formed in order to find prevalence and subtypes of Cryptosporidium among children with diarrhea in Gonbad Kavoos City, Northern Iran. Methods: Diarrheic samples were collected from 547 children. The initial parasi-tological diagnosis was made based on detection of oocysts using the modified Ziehl-Neelsen acid-fast staining method. The positive microscopically samples were selected for sequence analysis of partial 60 kDa glycoprotein (gp60) gene. Results: Out of 547 collected samples, 27 (4.94) were positive for Cryptosporid-ium oocysts. Fifteen from 27 positive samples successfully amplified in PCR. Se-quences analysis of gp60 gene in 15 Cryptosporidium isolates revealed that all of them (100) were C. parvum. The results showed three subtypes of IIa subtype family (7 cases) including IIaA16G2R1, IIaA17G1R1, IIaA22G3R1 and one subtype of IId subtype family (8 cases). The most common allele was IId A17G1d (53.3). Conclusion: The predominance of zoonotic subtype families of C. parvum species (IIa, IId) in the present study is in concordance with previous studies in Iran and emphasizes the significance of zoonotic transmission of cryptosporidiosis in the country. © 2015, Tehran University of Medical Sciences (TUMS). All rights Reserved

    A STUDY OF THE FACTORS RELATED TO PURCHASE INTENTION OF COSMETICS CUSTOMERS IN THAILAND

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    This research strives to examine the factors that are related to the purchase intention of Thai female customers toward Thai cosmetics in Bangkok, Specifically, it focuses on Srichand, one of the most renowned local Thai cosmetic brand in Thailand, with high sales revenues. A total of 30 current customers were interviewed to collect data. The results were analyzed utilizing the descriptive and inferential statistics. The results illustrate that most of interviewees stated that this Thai brand has some features such as affordability, availability even in local grocery shops, good quality in terms of smoothness, strength of whitening, goodness in removing the facial acne, and more importantly the positivity of customer’s perception on the ingredients of Srichand brand which contains herbal substances. These all factors are related to purchase intention of Thai female customers. This study will be helpful to Thai local cosmetic manufacturers to have a better understanding of their consumers’ behavior

    Bifurcation analysis and nonlinear dynamics of a capacitive energy harvester in the vicinity of the primary and secondary resonances

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    The objective of the present study is to examine the effect of nonlinearity on the efficiency enhancement of a capacitive energy harvester. The model consists of a cantilever microbeam underneath which there is an electret layer with a surface voltage, which is responsible for the driving energy. The packaged device is exposed to unwanted harmonic mechanical excitation. The microbeam undergoes mechanical vibration, and accordingly, the energy is harvested throughout the output electric circuit. The dynamic formulation accounts for nonlinear curvature, inertia, and nonlinear electrostatic force. The efficiency of the device in the vicinity of the primary and super-harmonic resonances is examined, and accordingly, the output power is evaluated. Bifurcation analysis is carried out on the dynamics of the system by detecting the bifurcations in the frequency domain and diagnosing their respective types. One of the challenging issues in the design and analysis of energy-harvesting devices is to broaden the bandwidth so that more frequencies are potentially accomodated within the amplification region. In this study, the effect of the nonlinearity on the bandwidth broadening, as well as efficiency improvement of the device, are examined. It is seen that as the base excitation amplitude increases, the vibration amplitude does also increase and accordingly the nonlinearity dominates. The super-harmonic resonance regions emerge and get bigger as the vibration amplitude increases, and pull-in gaps appear in the frequency response curves

    Effectiveness of Simple to Complex Sequences and Composition Instructional Strategies in Learning and Retention of Concept of Experimental Science in Secondary School

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    The present study aimed to investigates the impact of simple to complex sequencing strategies and composition on the learning and retention of concepts of experimental science lesson in secondary school. In this study, two groups of semi-experimental design with pre-test and post-test were used. Statistical population was all second year male students of public schools of Kaleibar city in school year of 2000-2001. From this community, with a multi-stage cluster sampling method, two classes were selected as samples. In this study to assess subjects, academic achievement test was used and to assess its validity the opinions of scholars, related experts, and the two dimensional table of content-aim is used and the reliability of measuring instrument by the correlation between two halves of pre-test and post- test is obtained 0/83 and 0/84 respectively. The research procedure was in this way that the experimental group was trained the chapter 13 of experimental science book of secondary school by using of simple to complex sequencing strategies and composition and control groups received the same chapter through the traditional teaching method. At the end, after performing a post-test and analysis of covariance of obtained data, it was found that, there was a significant difference between learning rate of experimental and control groups in experimental science lesson and experimental group meet better learning and the results showed that students in the experimental group compared to the control group performed better in post-test of retention
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