EFFICIENT NUMERICAL ANALYSIS BASED ON PERTURBATION METHOD FOR THE EFFECT OF WAVINESS IN CFRP

The paper proposes a numerical multiscale homogenization method for carbon fiber reinforced composites, where fiber alignment is disturbed due to unintended imperfections (fiber waviness). Imperfection is introduced as input to the calculation, and the calculation is always done using idealized perfect geometry. This has a distinct advantage in numerical calculations where the same mesh can be used for a series of imperfect geometries. The calculation is based on second-order perturbation method in order to capture the anisotropy which is the feature of CFRP. The proposed method is validated by comparing the results to those of a conventional calculation. The results demonstrate that the proposed method can accurately capture the stress distribution when the amplitude of the imperfection is small.

Accurate Realtime Motion Estimation Using Optical Flow on an Embedded System

Motion estimation has become one of the most important techniques used in realtime computer vision application. There are several algorithms to estimate object motions. One of the most widespread techniques consists of calculating the apparent velocity field observed between two successive images of the same scene, known as the optical flow. However, the high accuracy of dense optical flow estimation is costly in run time. In this context, we designed an accurate motion estimation system based on the calculation of the optical flow of a moving object using the Lucas–Kanade algorithm. Our approach was applied on a local treatment region implemented into Raspberry Pi 4, with several improvements. The efficiency of our accurate realtime implementation was demonstrated by the experimental results, showing better performance than with the conventional calculation.

PERBANDINGAN PERHITUNGAN VOLUME PEKERJAAN DAK BETON BERTULANG ANTARA METODE BIM DENGAN KONVENSIONAL

With the development of technologies, some engineers still have a limit about technologies that can help them on their project. One of the technologies in the construction field is Building Information Modelling (BIM). BIM is an innovation from Information Communication Technology (ICT) in the construction world. Applications from BIM used in this research are Cubicost Take-off Architecture & Structure (TAS) for concrete working volume calculation and Cubicost Take-off Reinforcement Bar (TRB) for reinforcement working volume calculation. In this research, the writer aims to compare the calculation of roof plate working volume between the Building Information Modeling method with the conventional method. On concrete working volume calculation with Cubicost TAS, the calculation has the same number as conventional calculation or having 0% differential. The working volume calculation between Cubicost TRB and conventional calculation has an accurate result with a differential of 0.59% on reinforcement. The calculation process with Cubicost, which has an automatic system, is shorter and not taking much time than the conventional one, which has a step-by-step process and formula that the writer should be studied first. ABSTRAKSeiring berkembangnya teknologi, masih terdapat engineer yang dapat dikatakan terbatas dalam pengetahuan teknologi yang dapat membantu pengerjaan proyek mereka. Salah satu teknologi yang ada pada bidang konstruksi merupakan penggunaan Building Information Modeling (BIM). BIM merupakan salah satu inovasi yang termasuk dalam bidang Information Communication Technology (ICT) yang berada pada dunia konstruksi. Aplikasi BIM yang digunakan pada penelitian ini adalah Cubicost Take-off Architecture & Structure (TAS) untuk perhitungan volume kebutuhan beton dan Cubicost Take-off Reinforcement Bar (TRB) untuk perhitungan volume kebutuhan besi. Penelitian ini bertujuan untuk membandingkan perhitungan volume pekerjaan dak beton bertulang antara metode Building Information Modeling dengan konvensional untuk mengetahui manfaat dari penggunaan BIM pada perhitungan volume pekerjaan dak beton bertulang. Pada perhitungan kebutuhan volume beton dengan aplikasi Cubicost TAS, perhitungannya menghasilkan angka yang sama dengan perhitungan konvensional atau perbedaan 0%. Pada perhitungan kebutuhan berat besi untuk pekerjaan pembesian antara aplikasi Cubicost TRB dengan perhitungan konvensional menghasilkan hasil yang akurat dengan perbedaan 0.59%. Proses perhitungan dengan Cubicost yang memiliki sistem otomasi dapat dikatakan lebih singkat dan tidak memakan waktu jika dibandingkan dengan konvensional yang membutuhkan cara pengerjaan satu per satu dan rumus yang perlu dipahami terlebih dahulu.

Towards an improved treatment of cloud-radiation interaction in weather and climate models: exploring the potential of the Tripleclouds method for various cloud types using libRadtran 2.0.4

Although the representation of unresolved clouds in radiation schemes of coarse-resolution weather and climate models has progressed noticeably over the past years, a lot of room remains for improvement, as the current picture is by no means complete. The main objective of the present study is to advance the cloud-radiation interaction parameterization, focusing on the issues related to model misrepresentation of cloud horizontal inhomogeneity. This subject is addressed with the state-of-the-art Tripleclouds radiative solver, the fundamental feature of which is the inclusion of the optically thicker and thinner cloud fraction, where the thicker is associated with the presence of convective updraft elements. The research challenge is to optimally set the pair of cloud condensates characterizing the two cloudy regions and the corresponding geometrical split of layer cloudiness. A diverse cloud field data set was collected for the analysis, comprising case studies of stratocumulus, cirrus and cumulonimbus. The primary goal is to assess the validity of global cloud variability estimate along with various condensate distribution assumptions. More sophisticated parameterizations are subsequently explored, optimizing the treatment of overcast as well as extremely heterogeneous cloudiness. The radiative diagnostics including atmospheric heating rate and net surface flux are consistently studied using the Tripleclouds method, evaluated against a three-dimensional radiation computation. The performance of Tripleclouds mostly significantly surpasses the conventional calculation on horizontally homogeneous cloudiness. The effect of horizontal photon transport is further quantified. The overall conclusions are intrinsically different for each particular cloud type, encouraging endeavors to enhance the use of cloud regime dependent methodologies in next-generation atmospheric models. This study highlighting the Tripleclouds potential for three essential cloud types signifies the need for more research examining a broader spectrum of cloud morphologies.

Exact and fast calculation of the X-ray pair distribution function

A fast and exact algorithm to calculate the powder pair distribution function (PDF) for the case of periodic structures is presented. The new algorithm calculates the PDF by a detour via reciprocal space. The calculated normalized total powder diffraction pattern is transferred into the PDF via the sine Fourier transform. The calculation of the PDF via the powder pattern avoids the conventional simplification of X-ray and electron atomic form factors. It is thus exact for these types of radiation, as is the conventional calculation for the case of neutron diffraction. The new algorithm further improves the calculation speed. Additional advantages are the improved detection of errors in the primary data, the handling of preferred orientation, the ease of treatment of magnetic scattering and a large improvement to accommodate more complex instrumental resolution functions.

Computation of Analytical Zoom Locus Using Padé Approximation

When the number of lens groups is large, the zoom locus becomes complicated and thus cannot be determined by analytical means. By the conventional calculation method, it is possible to calculate the zoom locus only when a specific lens group is fixed or the number of lens groups is small. To solve this problem, we employed the Padé approximation to find the locus of each group of zoom lenses as an analytic form of a rational function consisting of the ratio of polynomials, programmed in MATLAB. The Padé approximation is obtained from the initial data of the locus of each lens group. Subsequently, we verify that the obtained locus of lens groups satisfies the effective focal length (EFL) and the back focal length (BFL). Afterwards, the Padé approximation was applied again to confirm that the error of BFL is within the depth of focus for all zoom positions. In this way, the zoom locus for each lens group of the optical system with many moving lens groups was obtained as an analytical rational function. The practicality of this method was verified by application to a complicated zoom lens system with five or more lens groups using preset patents.

On the Kelvin Transformation in Finite Difference Implementations

Finite difference operators were applied on a Delaunay mesh. This way it is possible to discretize a radial boundary that is used to perform a Kelvin mapping of an additional outer domain to virtually extend the computation domain to infinity. With an example two-wire problem, the performance of this approach is shown in comparison with a conventional calculation domain and with the analytical solution, respectively. The presented implementation delivers a more precise approximation to the real values and at the same time requires a smaller system of equations—i.e., allows for faster computations.

Monte Carlo Simulation Approach to the Duration of Yellow Lights at Signalized Intersections Considering the Stochastic Characteristics of Drivers

In China, around 90% of traffic crashes at signalized intersections take place within the signal change intervals, especially during signal change from green to red. Hence, yellow time, which is a part of inter-green time, is of great significance to the safety of signalized intersections. The conventional calculation method for duration of yellow light (DYL) ignores the stochastic characteristics of drivers, which we believe is an important factor in this calculation. Therefore, the purpose of this research is to investigate a new approach to calculate DYL based on safety reliability theory in which the randomness of human factors is taken into consideration. Firstly, a comprehensive literature review concerning the conventional calculation methods of DYL is conducted. Secondly, a theoretical calculation method of DYL based on safety reliability theory is put forward which, different from the conventional methods, accounts for the stochastic characteristics of drivers. Additionally, a driving simulation experiment is designed to obtain two driving behavior parameters of Chinese drivers: perception–reaction time (PRT) and safe acceptable acceleration (SAA). Thirdly, a Monte Carlo simulation is employed to simulate the interactive process of PRT and SAA, and solve the proposed model. Finally, according to the Monte Carlo simulation results, a look-up table describing the relationship between DYL, safety reliability (50–90%) and approaching speed (15–40 km/h) is made. Results show that this method successfully incorporates the probabilistic nature of driving behavior. Taking the safety reliability into consideration can provide a more reasonable method to calculate the DYL of signalized intersections.

Intergreen Time Calculation Method of Signalized Intersections Based on Safety Reliability Theory: A Monte-Carlo Simulation Approach

In China, around ninety percent of the traffic accidents at signalized intersections occur within the signal change intervals, especially during signal change from green to red. Hence, intergreen time (IGT), that is, yellow change interval plus red clearance interval, is of great significance to the safety at signalized intersections. The conventional calculation method of IGT ignores the randomness of drivers’ behaviors, which we believe is an important factor in calculation of IGT. Therefore, the purpose of this research is to investigate a new approach to calculate the IGT based on safety reliability theory. Firstly, a comprehensive literature review concerning the conventional calculation methods of IGT is conducted. Secondly, a theoretical calculation method of IGT based on safety reliability theory is put forward; different from the conventional methods, this model accounts for the uncertainty of driving behavior parameters. Thirdly, a Monte-Carlo simulation is employed to simulate the interactive process of perception-reaction time (PRT) and vehicular deceleration and solve the proposed model. Finally, according to the Monte-Carlo simulation results, the curve clusters describing the relationship between IGT, safety reliability (50%-90%), and intersection width (15-35m) are drawn. Results show that the IGT of a signalized intersection, obeying the normal distribution, is influenced by multiple factors and most sensitive to the PRT and vehicular deceleration. Our method thus successfully incorporates the probabilistic nature of driving behavior. Taking the safety reliability into consideration can provide a more reasonable method to calculate the IGT of signalized intersections.

Lebensdauer von Profilschienenführungen* – Teil 1/Lifespan of profile rail guides – Developing of a simplified rolling contact related life calculation for profile rail guides

Die Berechnung der Lebensdauer von Profilschienenführungen (PSF) ist bei der Anlagenauslegung ein wesentlicher Bestandteil. Bei der wälzkontaktbezogenen Lebensdauerrechnung (WKBL) wird die Überlebenswahrscheinlichkeit jedes Wälzkontaktes berücksichtigt, was bei bestimmten Anordnungen von PSF, unter Momentenbelastung, bis zu 4-fach höhere Lebensdauerwerte als eine konventionelle Berechnung liefert. Neue mathematische Modelle erlauben eine adaptierbare und anwenderfreundliche Berechnung der WKBL.   Calculating the life span of profile rail guides is an essential part in designing new mechanical systems. The ‚rolling contact related life calculation‘ (RCRL) takes into account the survival probability of each rolling contact. This allows for calculating life spans up to four times higher than by conventional calculation methods for pitch and yaw moments on single profile rail guides. New mathematical models enable an adaptable and user-friendly calculation of RCRL.