Microtremor surveys based on rotational seismology: theoretical analysis with focus on separation of Rayleigh and Love waves in general wavefield of microtremors

SUMMARY The applicability of rotational seismology to the general wavefield of microtremors is theoretically demonstrated based on a random process model of a 2-D wavefield. We show the effectiveness of taking the rotations (i.e. spatial differentiation) of microtremor waveforms in separating the Rayleigh and Love waves in a wavefield where waves are simultaneously arriving from various directions with different intensities. This means that a method based on rotational seismology (a rotational method) is capable of separating Rayleigh and Love waves without adopting a specific array geometry or imposing a specific assumption on the microtremor wavefield. This is an important feature of a rotational method because the spatial autocorrelation (SPAC) method, a conventional approach for determining phase velocities in microtremor array surveys, requires either the use of a circular array or the assumption of an isotropic wavefield (i.e. azimuthal averaging of correlations is required). Derivatives of the SPAC method additionally require the assumption that Rayleigh and Love waves are uncorrelated. We also show that it is possible to apply a rotational method to determine the characteristics of Love waves based on a simple three-point microtremor array that consists of translational (i.e. ordinary) three-component sensors. In later sections, we assume realistic data processing for microtremor arrays with translational sensors to construct a theoretical model to evaluate the effects of approximating spatial differentiation via finite differencing (i.e. array-derived rotation, ADR) and the effects of incoherent noise on analysis results. Using this model, it is shown that in a short-wavelength range compared to the distance for finite differencing (e.g. $\lambda < 3h$, where $\lambda $ and $h$ are the wavelength and distance for finite differencing, respectively), the leakage of unwanted wave components can determine the analysis limit. It is also shown that in a long-wavelength range (e.g. $\lambda > 3h$), the signal intensity gradually decreases, and thus the effects of incoherent noise increase (i.e. the signal-to-noise ratio, SNR decreases) and determine the analysis limit. We derive the relation between the SNR and wavelength. Although the analysis results quantitatively depend on the array geometry used for finite differencing, the qualitative understanding supported by mathematical expressions with a physically clear meaning can serve as a guideline for the treatment of data obtained from ADR.

Analisis Persentase Penghematan Air Irigasi dengan Metode Pergiliran (Magilihan) pada Subak di DAS Ho

ABSTRAK Berkurangnya ketersediaan air irigasi dapat disebabkan oleh debit air sungai yang turun pada musim kemarau, hilangnya air pada saluran irigasi, dan evaporasi. Dengan demikian, upaya-upaya penghematan perlu dilakukan seperti sistem pergiliran dalam pemberian air irigasi dan proposi dalam ditribusi air irigasi pada setiap subak. Penelitian dilakukan untuk mengetahui persentase pengehematan air irigasi yang ada pada suatu subak dan proposi pemberian air irigasi pada saat kurangnya ketersediaan air. Perolehan data primer dilakukan dengan metode wawancara, pengamatan, dan pengukuran sedangkan data sekunder diperoleh dari BMKG Wilayah III Denpasar. Data yang dikumpulkan selanjutnya akann dianalisis untuk mencari persentase pengehematan yang terjadi pada saat kekurangan air dan proposi distribusi air irigasi. Hasil penelitian menunjukan metode pergiliran dilakukan pada saat debit air tersedia tidak bisa memenuhi kebutuhan air irigasi. Metode pergiliran dilakukan pada subak bagian tengah dan subak bagian hulu pada bulan April sampai Mei. Metode pergiliran dilakukan dengan menurunkan jumlah kebutuhan air irigasi dan memberikan air irigasi sesuai dengan debit tersedia dengan rentang waktu setiap dua hari. Subak bagian hulu tidak terjadi penghematan karena proses pergiliran tidak berjalan, penghematan air irigasi pada subak bagian tengah rata-rata sebesar 28,3 persen dan subak bagian hilir sebesar 24 persen. Dengan penerapan metode pergiliran pada saat kekurangan air irigasi kebutuhan air irigasi bisa terpenuhi oleh debit air yang tersedia. Untuk mencapai proposional penghemtan air irigasi pada bulan April sampai Mei, pada subak bagian hulu air irigasi diturunkan sebesar 17,46 persen, subak tengah dinaikan 13,37 persen, dan subak hilir dinaikan 9,84 persen. ABSTRACT Availability of irrigation water can be influenced by the discharge of river water that drops in the dry season, loss of water in irrigation channels and evaporation. Thus, austerity measures need to be made such as a system of turns in irrigation water and balanced in the attribution of irrigation water on each subak. Research was conducted to determine the percentage of irrigation water storage present in a subak and the proportion of irrigation water at a time of lack of water availability. The acquisition of primary data is done by interviewing, observation, and measurement methods while secondary data is obtained from BMKG Region III Denpasar. The data collected will then be analyzed to look for the percentage of storage that occurs during water shortages and the balanced of irrigation water distribution. The results showed the method of turns was carried out when the discharge of available water could not meet the needs of irrigation water. The turns method occurs in the middle and upper subak from April to May. The method of turns is carried out by lowering the amount of irrigation water needs and providing irrigation water according to the discharge available with a time span every two days. The upstream subak does not have any savings because the rotating process is not running, irrigation water savings in the central subak averaged 28,3 percent and downstream subak by 24 percent. Water rotational method can be used when there is a shortage of irrigation water, therefor water needs can be met by the discharge of available water. To achieve the proportional irrigation water supply in April to May, the upper subak of irrigation water was lowered by 17,46 percent, the central subak was increased by 13,37 percent, and the downstream subak was increased by 9,84.

Nonlinear numerical model of plane frames considering semi-rigid connection and different beam theories

ABSTRACT This paper presents a numerical-computational model for frames with geometric nonlinear behavior, by the Finite Element Co-rotational method, considering the Euler-Bernoulli and Timoshenko beam theories. The connection between structural members is simulated by a null-length connection element, which considers the axial, translational and rotational stiffness. The nonlinear equations system that describes the structural problem is solved by the incremental and iterative procedure of Potra-Pták, with cubic convergence order, combined with the Linear Arc-Length path-following technique. The solution method algorithm is presented and the numerical examples are simulated with the free Scilab program. The numerical results show that the slenderness of the structure, geometric nonlinearity and semi-rigidity influence the behavior of the structure. Structural analysis and design procedures that consider these factors attains less conservative design thus obtaining more optimized structures.

Analysis of the Abrasive-Type Influence on the Effectiveness of Rotary Cleaning of Machine Parts with Complex Geometric Features

This work presents the analysis of functional relationships between fraction size of abrasives and geometric parameters of surfaces after rotary cleaning. The influence of an abrasive type on the effectiveness of rotary cleaning of machine parts with complex geometric features was determined as well. The process of mechanical cleaning, using a rotational method, of clutch springs was performed in the proprietary device for rotational cleaning, which was followed by the computer-aided analysis of the obtained results. The research process was carried out using abrasive materials such as grinding stone, sand, basalt, glass, and fine gravel, and the test samples were clutch springs after eight years of operation. Based on calculated three-dimensional (3D) roughness values of the cleaned samples’ surfaces, qualitative classification of abrasives was determined. The most effective material turned out to be fine gravel, while the worst results were related to basalt usage.

Analyzing Malaria Disease Using Effective Deep Learning Approach

Medical tools used to bolster decision-making by medical specialists who offer malaria treatment include image processing equipment and a computer-aided diagnostic system. Malaria images can be employed to identify and detect malaria using these methods, in order to monitor the symptoms of malaria patients, although there may be atypical cases that need more time for an assessment. This research used 7000 images of Xception, Inception-V3, ResNet-50, NasNetMobile, VGG-16 and AlexNet models for verification and analysis. These are prevalent models that classify the image precision and use a rotational method to improve the performance of validation and the training dataset with convolutional neural network models. Xception, using the state of the art activation function (Mish) and optimizer (Nadam), improved the effectiveness, as found by the outcomes of the convolutional neural model evaluation of these models for classifying the malaria disease from thin blood smear images. In terms of the performance, recall, accuracy, precision, and F1 measure, a combined score of 99.28% was achieved. Consequently, 10% of all non-dataset training and testing images were evaluated utilizing this pattern. Notable aspects for the improvement of a computer-aided diagnostic to produce an optimum malaria detection approach have been found, supported by a 98.86% accuracy level.

On the co-rotational method for geometrically nonlinear topology optimization

This paper investigates the application of the co-rotational method to solve geometrically nonlinear topology optimization problems. The main benefit of this approach is that the tangent stiffness matrix is naturally positive definite, which avoids some numerical issues encountered when using other approaches. Three different methods for constructing the tangent stiffness matrix are investigated: a simplified method, where the linear elastic stiffness matrix is simply rotated; the consistent method, where the tangent stiffness is derived by differentiating residual forces by displacements; and a symmetrized method, where the consistent tangent stiffness is approximated by a symmetric matrix. The co-rotational method is implemented for 2D plane quadrilateral elements and 3-node shell elements. Matlab code is given in the appendix to modify an existing, freely available, density-based topology optimization code so it can solve 2D problems with geometric nonlinear analysis using the co-rotational method. The approach is used to solve four benchmark problems from the literature, including optimizing for stiffness, compliant mechanism design, and a plate problem. The solutions are comparable with those obtained with other methods, demonstrating the potential of the co-rotational method as an alternative approach for geometrically nonlinear topology optimization. However, there are differences between the methods in terms of implementation effort, computational cost, final design, and objective value. In summary, schemes involving the symmetrized tangent stiffness did not outperform the other schemes. For problems where the optimal design has relatively small displacements, then the simplified method is suitable. Otherwise, it is recommended to use the consistent method, as it is the most accurate.

Inter-Segmental Coordination during a Unilateral 180° Jump in Elite Rugby Players: Implications for Prospective Identification of Injuries

Musculoskeletal injuries often occur during the execution of dynamic sporting tasks that involve rotation. The prescription of appropriate prevention strategies of musculoskeletal injury relies on assessments to identify risk, but current assessment tools focus on uniplanar movements. The purpose of this paper is to demonstrate the utility of the unilateral 180° jump as a potential assessment tool for injury risk in the lower body by (1) providing descriptive kinematics of the knee, thigh, and pelvis (2) conducting inter-segmental coordination analysis, and (3) comparing the knee kinematics between the dominant and non-dominant limb (NDL) during the loading (LOP) and landing phase (LAP). Elite rugby players completed one session, performing five 180° unilateral jumps on each limb while collecting kinematic data. Independent t-tests were used to compare peak angles of DL and NDL. Continuous Relative Phase (CRP) plots were constructed for thorax and pelvis in the transverse plane. At the loading phase, the non-dominant limb had greater peak knee abduction (ABD) (p = 0.01). At the landing phase, the dominant limb had greater peak knee adduction (ADD) (p = 0.05). At the landing phase, the non-dominant limb had greater peak knee ABD (p = 0.01). CRP plots indicate participants can utilize a thorax-led, pelvis-led, or synchronized rotational method. Bilateral asymmetries were observed, indicated by significant differences in the bilateral landing phase peak ADD/ABD, which is of particular interest considering all participants were healthy. Therefore, additional research is needed to determine thresholds for injury risk during rotational tasks.