How to cluster in parallel with neural networks

Partitioning a set of N patterns in a d-dimensional metric space into K clusters - in a way that those in a given cluster are more similar to each other than the rest - is a problem of interest in astrophysics, image analysis and other fields. As there are approximately K(N)/K (factorial) possible ways of partitioning the patterns among K clusters, finding the best solution is beyond exhaustive search when N is large. Researchers show that this problem can be formulated as an optimization problem for which very good, but not necessarily optimal solutions can be found by using a neural network. To do this the network must start from many randomly selected initial states. The network is simulated on the MPP (a 128 x 128 SIMD array machine), where researchers use the massive parallelism not only in solving the differential equations that govern the evolution of the network, but also by starting the network from many initial states at once, thus obtaining many solutions in one run. Researchers obtain speedups of two to three orders of magnitude over serial implementations and the promise through Analog VLSI implementations of speedups comensurate with human perceptual abilities

Amyloid Aggregation Behavior of Human Calcitonin

Under appropriate conditions, certain peptides and proteins, both intrinsically disordered and misfolded from their native state, can self-associate to form long proteinaceous fibrils known as amyloids. This transition forms the molecular basis of several pathologies, through both losses of native functions and cytotoxic effects. Calcitonin (CT) is a 32 amino acid therapeutic hormone peptide that can be considered a molecular paradigm for the central events associated with amyloid misfolding. CT’s biological activity is limited by its aggregation along the canonical amyloid aggregation pathway. A better understanding of the misfolding process would not only provide a structural basis to improve CT’s long-term stability and activity as a therapeutic, but also provide valuable insights into the pathological aggregation of other amyloids. As such, the aggregation of human CT (hCT) has been studied in this dissertation using a range of biophysical techniques, with a particular focus on native modulators of kinetic behavior. A direct relationship between human calcitonin (hCT) concentration and aggregation lag time was observed for the first time, contrary to the conventional understanding of amyloid aggregation. This kinetic trend was found to persist over a range of aggregation conditions, as confirmed by Thioflavin-T kinetics assays, CD spectroscopy, and transmission EM. On the basis of kinetics modeling and experimental results, a mechanism whereby structural conversion of hCT monomers is needed before incorporation into the fibril was proposed. Comparative studies of hCT and the canonically aggregating salmon CT (sCT) using experimental and computational techniques suggested that alpha-helical monomers represent a growth-competent species, whereas unstructured random coil monomers represent a growth-incompetent species. The kinetic mechanism proposed represents a novel mechanism in amyloid aggregation, and synthesizes several previously disparate amyloid behaviors. The determinants of hCT lag time were further investigated in a membrane environment, providing the first systematic study of the effect of membranes on CT aggregation. The direct relationship between peptide concentration and lag phase was found to persist in the presence of large unilamellar vesicles (LUVs), and was shown to be dependent on membrane composition. Specifically, lipid compositions encouraging stronger surface interactions increased the concentration dependent differences in lag time. CD experiments suggested adsorption and sequestration of growth-competent helical monomers to play a role in this behavior. An apparent reformatting of mature hCT fibrils was also observed, in a process which appears dependent on not only lipid composition but also the peptide to lipid ratio. The ability of LUVs to remodel fibers grown in solution suggests that interactions between mature fibrils and lipid bilayers are causative in the behavior, rather than membrane-peptide interactions during fiber growth. The results of this thesis, particularly as they relate to monomer growth competence, represent significant contributions to the amyloid field and CT therapy. The novel kinetic mechanism proposed reveals that intramolecular interactions in disordered monomers, while often transient and weak compared to intermolecular interactions, can play crucial roles in mediating amyloid aggregation. Additionally, the elucidated effects of monomer structure and lipid interactions on hCT aggregation kinetics present possible means by which aggregation kinetics can be modulating while maintaining peptide sequence and thus therapeutic efficacy, a key goal in hCT therapies. Such results present a richer picture of hCT aggregation than had previously been available, and potentially provide novel insights as to more general mechanisms of amyloid aggregation.PHDApplied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/144023/1/kkamgar_1.pd

Improvement of the Results of Finite Element Method in Plate Analysis Using Mesh Sizing Modifying Function

In the finite element methods (FEM), the mesh dimension, and the number of elements can affect the responses of structures. In this paper, a procedure is proposed to modify the stiffness matric of the plate element based on the mesh geometry and mesh size for reducing the central deflection error. For this purpose, the modifying coefficients are defined for the bending and shear stiffness matrices. The sensitivity of coefficients is investigated when the thickness of the plate element, the mesh dimension, and also the type of supports vary. The analysis results prove that the values of the bending coefficient have more effect in comparison to the shear coefficient. Finally, a function is proposed to determine the bending and shear matric coefficients based on the values of the exact displacements. Various numerical studies indicate that the modifying function has significantly improved the performance of the plate element, especially for the plates with irregular and large mesh dimensions

A Case of Reactive Cervical Lymphadenopathy with Fat Necrosis Impinging on Adjacent Vascular Structures.

A tender neck mass in adults can be a diagnostic challenge due to a wide differential diagnosis, which ranges from reactive lymphadenopathy to malignancy. In this report, we describe a case of a young female with an unusually large and tender reactive lymph node with fat necrosis. The diagnostic imaging findings alone mimicked that of scrofula and malignancy, which prompted a complete workup. Additionally, the enlarged lymph node was compressing the internal jugular vein in the setting of oral contraceptive use by the patient, raising concern for Lemierre's syndrome or internal jugular vein thrombosis. This report shows how, in the appropriate clinical context, and especially with the involvement of adjacent respiratory or neurovascular structures, aggressive diagnostic testing can be indicated

Wavelet-based Decomposition of Ground Acceleration for Efficient Calculation of Seismic Response in Elastoplastic Structures

The nonlinear dynamic analysis provides a more accurate simulation of the structural behavior against earthquakes. On the other hand, this analysis method is time-consuming since the time-step integration schemes are used to calculate the responses of the structure. Wavelet transform is also considered as one of the strong computing tools in studying the properties of the waves. The continuous wavelet transform is a time-frequency study and examines the frequency content of the waves while, the discrete wavelet transform is used to reduce sampling data and also to eliminate the noise of the waves. In this paper, the discrete and continuous wavelet transforms are used to reduce the wave sampling and therefore to reduce the required time for analysis. In this regard, eight near- and far- field earthquakes are studied. The frequency content of the earthquake is investigated by the Fourier spectrum and the continuous wavelet transform. The results show that the first five frequencies for the main earthquakes are similar to those values of earthquakes obtained by wavelet transform. Besides, it is shown that using wavelet transform for the main and decomposed earthquakes indicates that the duration of strong ground motion and the time of dominant frequency occur approximately in the same domain. Finally, it is concluded that the required calculation time reduces to about 80 % with an error less than 6 % when the main earthquake is decomposed by wavelet transform and the approximation waves are used in the nonlinear dynamic analysis

Optimal Location of Energy Dissipation Outrigger in High-rise Building Considering Nonlinear Soil-structure Interaction Effects

Buckling-restrained braces (BRBs) emerged to improve the seismic performance of high-rise structures as compared to the ordinary diagonal bracing. In this paper, the seismic performance of braced buildings with the BRB outrigger system is investigated to determine the optimal configuration of BRB outrigger, considering the nonlinear SSI effect. For this purpose, the nonlinear dynamic analysis is carried out on four braced buildings with a BRB outrigger system placed on three different soil types. The outrigger configuration changes from first to the top story to capture the seismic performance of different locations of BRB outrigger. It is observed that the outrigger location affects the seismic performance, which is measured in terms of inter-story drift ratio, story displacement, story shear, and energy dissipation capacity. The results are compared to the fixed base condition buildings, which proves considering SSI, shifts the optimal location to the upper story of the structure. Moreover, the effect of soil’s stiffness on the seismic responses of structures and the optimal BRB outrigger location is investigated. Finally, the merits of BRB outrigger are shown by comparing its seismic performance that of the conventional outrigger, under frequent, basic, and rare earthquakes. The results show that the optimal locations of different 2-D buildings rested on the dense soil, medium soil, and soft clay are obtained at 0.6, 0.65, and 0.7 of the building’s height (H), respectively. Also, the results show that the optimum location of the BRB outrigger system based on the energy dissipation criteria is 0.45H to 0.65H

The Best Location of Belt Truss System in Tall Buildings Using Multiple Criteria Subjected to Blast Loading

The main goal of this paper is to investigate the effect of blast phenomenon on structures to determine the best location of belt truss system in tall buildings. For this purpose, one of the exterior frames of a tall steel building, in which the belt truss is located, is considered. The steel frame model is subjected to two different charges of equivalent weight which are applied in two different standoff distances. In this research, the best location of the belt truss system is determined using OpenSees software based on the nonlinear dynamic analysis. The best location of the belt truss system for different types of loading is investigated both with and without considering the post-buckling effect for all members of the belt truss system. The results show that when blast charges are located in a 5-meter range from the building (R=5), post buckling effect of truss elements are more obvious than the case in which blast charges are located in a 10-meter range (R=10); this, in turn, causes the amount of base moment to be completely different when the belt truss is located in the first storey in comparison to the cases where the belt truss is located in any other stories. In addition, if the explosion occurs near the building when the base moment is considered as a criterion, the post buckling effect has a significant role

Finite Element Analysis of Functionally Graded Beams using Different Beam Theories

The present study deals with buckling, free vibration, and bending analysis of Functionally Graded (FG) and porous FG beams based on various beam theories. Equation of motion and boundary conditions are derived from Hamilton’s principle, and the finite element method is adopted to solve problems numerically. The FG beams are graded through the thickness direction, and the material distribution is controlled by power-law volume fraction. The effects of the different values of the power-law index, porosity exponent, and different boundary conditions on bending, natural frequencies and buckling characteristics are also studied. A new function is introduced to approximate the transverse shear strain in higher-order shear deformation theory. Furthermore, shifting the position of the neutral axis is taken into account. The results obtained numerically are validated with results obtained from ANSYS and those available in the previous work. The results of this study specify the crucial role of slenderness ratio, material distribution, and porosity condition on the characteristic of FG beams. The deflection results obtained by the proposed function have a maximum of six percent difference when the results are compared with ANSYS. It also has better results in comparison with the Reddy formulae, especially when the beam becomes slender. Doi: 10.28991/cej-2020-03091604 Full Text: PD

Design, development and field assessment of a controlled seed metering unit to be used in grain drills for direct seeding of wheat

AbstractA new controlled seed metering unit was designed and mounted on a common grain drill for direct seeding of wheat (DSW). It comprised the following main parts: (a) a variable-rate controlled direct current motor (DCM) as seed metering shaft driver, (b) two digital encoders for sensing the rotational speed of supplemental ground wheel (SGW) and seed metering shaft and (c) a control box to handle and process the data of the unit. According to the considered closed-loop control system, the designed control box regularly checked the revolution per minute (RPM) of seed metering shaft, as operation feedback, using its digital encoder output. The seeding rate was determined based on the calculated error signal and output signal of the digital encoder of the SGW. A field with four different levels of wheat stubble coverage (10%, 30%, 40% and 50%) was selected for evaluation of the fabricated seed metering unit (FSMU). The dynamic tests were conducted to compare the performance of installed FSMU on the grain drill and equipped grain drill with common seed metering unit (CSMU) at three forward speeds of 4, 6 and 8 (Km/h) for DSW. Results of the FSMU assessment demonstrated that an increase in forward speed of grain drill (FSGD) and stubble coverage did not significantly affect the seeding rate in the grain drill for DSW. Using the FSMU reduced the coefficient of variation (CV) by approximately 50%. Consequently, applying the FSMU on the common grain drill led to a desirable seeding rate at different forward speeds of the grain drill and stubble existence

A comparative study between mathematical models and the ANN data mining technique in draft force prediction of disk plow implement in clay loam soil

This paper communicates the prediction of required draft force of disk plow implement during tillage operations. The well-known mathematical model proposed by American Society of Agricultural and Biological Engineers (ASABE), multiple linear regression (MLR) and data mining model, based on artificial neural network (ANN), were employed for this purpose. The input variables of the models were considered as forward speed of 2-6 (km/h) and plowing depth of 10-30 (cm). The development details of the models are documented in the paper. On account of statistical performance criteria, the best ANN model with coefficient of determination of 0.971, root mean square error of 0.762 (kN), mean absolute percentage error of 1.886 (%) and mean value of absolute prediction residual errors of 0.968 (kN) was better performed than ASABE and MLR models for prediction of required draft force. The ANN modeling results also showed that the simultaneous or individual increment of forward speed and plowing depth caused nonlinear increment of draft force. The well-developed ANN model is considered operational to predict draft force as an essential step toward proper selection of combination of tractor and disk plow implement