1,721,516 research outputs found
Indole alkaloids and Sesterterpenoids from the unidentified Kosraean Marine Sponge
No full textThe extract from the unidentified Kosrean marine sponge was investigated as it exhibited cytotoxicity against MCF-7 and A375SM human cancer cell lines. The NMR-guided separation of this extract led to the isolation of twelve indole derivatives and seven scalarane sesterterpenoids. Among these, two alkaloids have never been reported from living organisms. The chemical structures of the isolated compounds were elucidated by comprehensive analysis of NMR and HRMS data. Sponge identification and measurement of biological activity for isolated compounds are in progress.2
Yaw/Heading optimization by Machine learning model based on MEMS magnetometer under harsh conditions
No full textThe paper's main goal is to accomplish a high accuracy of yaw/heading by Machine Learning approach when the motion range of vehicle/device calibration is limited. The nonlinear Random Forest (RF) Regression with proper training has a high potential to deal with the magnetometer uncertainty before calibration and during iron distortion cases. The proposed solution solely requires the magnetometer without other sensor's support. A Pan Tilt Unit-C46 (PTU-C46) with high precise positioning was used as a reference heading value to label the corresponding magnetic features in the learning model. The proposed approach helps yaw estimation to be carried out under harsh conditions, which resolve many difficulties in orientation tracking since the magnetometer is susceptible to hard iron and soft iron in the environment. In addition, many mechanical devices work only within the specific range and waste their dynamic motion around two axes or more just for calibration. Thus, the research focuses on the level rotation calibration around Z-axis within the restricted range of motion for practical application. The experiment was carried out using a low-cost platform equipped with Micro-Electro-Mechanical System (MEMS) sensors as gyroscope, accelerometer, and magnetometer. The 9 Degree of Freedom (DoF) Madgwick was implemented into the Microcontroller to compare with the proposed model. The sensor fusion can track the yaw value after the level calibration despite various error conduction. The RF model accomplishes a superior result with more stability and more minor error. Under iron disturbance or calibration absence, the ML model still maintains the good tracking command with maximum Mean Square Error of about 0.3°, while the Madgwick is unsuccessful in heading measurement due to huge error in these circumstances
Oral History of Long Hoang
No full textAn oral history with Long Hoang, born in 1984 in Saigon, Vietnam. He was sponsored to Colombia in 1990 by his uncle and moved to America in 1990. Long resides in Garden Grove. He has worked several different jobs while attending community college. He graduated from Divine Works College. As of this interview, Long is aspiring to become a priest, but was rejected from the divinity program of Divine Works College. Long is now in the process of re-applying to seminary school.Recorded Digitall
Multi-Wavelets Galerkin Method for Solving the System of Volterra Integral Equations
No full textIn this work, an efficient algorithm is proposed for solving the system of Volterra integral equations based on wavelet Galerkin method. This problem is reduced to a set of algebraic equations using the operational matrix of integration and wavelet transform matrix. For linear type, the computational effort decreases by thresholding. The convergence analysis of the proposed scheme has been investigated and it is shown that its convergence is of order O(2−Jr), where J is the refinement level and r is the multiplicity of multi-wavelets. Several numerical tests are provided to illustrate the ability and efficiency of the method
Energy characterization of attitude algorithms
No full textThe aim of this paper is to presents a comparison among three different algorithms of sensor data fusion based on Inertial Measurement Unit (IMU) looking at how they influence the energy consumption in an IMU platform. Complementary filter, Kalman filter and Quaternion filter have been considered for the aim using a low-cost platform equipped with Micro-Electro-Mechanical-system (MEMS) as gyroscope, accelerometer and magnetometer. The energy consumptions have been measured during both static and dynamic operations, using the industry-standard CoreMark performance benchmark with the ULPMark line of ultra-low-power benchmarks, reporting the difference among the considered algorithms
Pre-Processing Technique for Compass-less Madgwick in Heading Estimation for Industry 4.0
No full textThe high quality of heading orientation is a key factor to monitor the industrial robot arms in the Industry 4.0. The paper proposes a new algorithm ‘No Motion No Integration’ (NMNI) to enhance the gyroscope performance via signal processing and specifically improve the Madgwick filter for heading estimation to overcome the weakness of magnetometer and Global Navigation Satellite System (GNSS). The experiment was carried out to characterize the pros and cons of traditional Madgwick and new approached Madgwick. The results show that the proposed method displayed high effective measurements. The gyroscope drift was minimized to attain a good yaw angle without a magnetometer or GNSS
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Energy characterization of attitude algorithms
No full textThe aim of this paper is to presents a comparison among three different algorithms of sensor data fusion based on Inertial Measurement Unit (IMU) looking at how they influence the energy consumption in an IMU platform. Complementary filter, Kalman filter and Quaternion filter have been considered for the aim using a low-cost platform equipped with Micro-Electro-Mechanical-system (MEMS) as gyroscope, accelerometer and magnetometer. The energy consumptions have been measured during both static and dynamic operations, using the industry-standard CoreMark performance benchmark with the ULPMark line of ultra-low-power benchmarks, reporting the difference among the considered algorithms
Study on the Shear Strength of Partially Prestressed High Strength Concrete I Beams
No full textPartial prestressing, which fills the gap between fully prestressed concrete and reinforced concrete, has now been accepted and becomes common practice in many countries. Partial prestressing has now been recognized as an intermediate case between full prestressing and conventional (nonprestressed) reinforcing. Compared with fully prestressed concrete (FPC) structures, adoption of partial prestressing may result in increased ductility and energy absorption capacity, improved economy, as well as reduction of the camber and creep deformation due to prestress. This research aims to solve one of the most troublesome problems in partially prestressed concrete (PPC) beam, namely the shear problem. In fact, there is no rational model at present to predict the shear behavior of prestressed concrete structures and the strength of shear failures. Although there were a lot of studies and researches about shear strength in FPC beams but not much research about PPC beams in the world. Because of this deficiency, all the shear design provisions, such as those in the ACI 318-14 [1] and AASHTO LRFD Specification- 2012 [2], are empirical, complicated and have severe limitations. In this research, four full- scale prestressed high strength concrete I-beams were tested to study the effect of number of prestressing tendons and amounts of flexural nonprestressed steel. The cross section, web reinforcement, flexural ultimate moment, and shear span ratio (a/d) were held constants. The numbers of prestressing tendons and amounts of non-prestressed tensile were varied. The prestressing factor was defined by this equation: . Ap and As are the cross sectional areas of prestressed steel and non-prestressed tensile steel; and are the yield strength of prestressed steel and non-prestressed tensile steel. The results from these tests, together with those found in literature, were used to help the engineers have an overview about the behavior of shear strength in partially prestressed high strength concrete beam
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