Indirect Design Method Research Articles

Inverse design of dispersion for photonic devices based on LSTM and gradient-free optimization algorithms hybridization

As an inherent property of optical devices, dispersion plays an important role in the areas of optical communication and nonlinear optics. Traditional dispersion optimization approaches are time-consuming and power-hungry. In this paper, to accelerate the design of dispersive optical devices, an indirect inverse design method based on the long short-term memory forward model combined with gradient-free optimization algorithms is proposed. In the case of photonic crystal fiber, the results show that the forward model can predict the group velocity dispersion (GVD) with an accuracy of up to 99.62%, and the calculation speed is more than one thousand times faster than the conventional numerical simulations. The prediction accuracy of the inverse model is higher than 93%, with a calculation time of less than 20 s. In the case of slot waveguide, the results show that the forward model can predict the GVD with a prediction accuracy of 96.99% and the inverse design accuracy goes to 99%. The proposed machine learning model offers an efficient tool for dispersion optimization in both fiber and waveguide platforms.

Multiple laboratory characterization methods to identify the D-Load of reinforced concrete pipes based on three edge bearing tests

The indirect design method for concrete pipes, which estimates the bearing capacity of concrete pipes in a buried environment based on the D-load determined from a three-edge bearing test (TEBT), is a common method for designing concrete pipes. D-load is determined by the load corresponding to the first 3-mm crack, which has been used from the 1930s until today. To explore the potential of modern laboratory techniques as an alternative to the traditional vision method. This study discusses the application and cost-effectiveness of several technologies for detecting D-load, including strain gauges, displacement sensors, acoustic emission, digital image correlation, and infrared thermography, based on TEBT on full-scale double-cage reinforced concrete pipes with internal diameters of 1000, 1500, and 2000 mm. The consistency between D-load values obtained by these approaches along with the predicted value by Heger’s model is compared with the D0.3_visual determined by conventional visual observation in terms of the developed relative reliability. It is found that the method based on acoustic emission techniques is more consistent with the D0.3_visual than others, but is costly and time-consuming. Also, De, identified by the load corresponding to the end of the elastic phase of the force–time curve, is a reliable alternative and cost-effective method. This study will provide new insights into the aspect of performance design and evaluation for concrete pipes.

Experiment and evaluation model of liner design for renewal of deteriorated reinforced concrete pipes utilizing cured-in-place-pipe technology

Cured-In-Place-Pipe (CIPP) is an emerging trenchless rehabilitation technology for repairing urban drainage pipes growing significantly in China. However, overestimated external loads due to a completely deteriorated-pipe assumption may increase conservatism in the CIPP liner structure design. In this study, ring stiffness test machine was employed to quantify the bearing characteristics of pipe-liner system. The concrete and reinforced concrete pipes with an inner diameter of 200 mm, which deteriorated to several states, were renewed with CIPP. Digital Image Correlation (DIC) was employed to reveal the contact characteristics between the host pipe and CIPP liner under external loads and the mechanism of loads transferred from the pipe to the liner. An evaluation model for load-bearing performance of reinforced pipe was established. Parametric studies were carried out including lateral load distribution angle, concentrated load dispersed angle, and lateral interactions. Furthermore, a case study was conducted in conjunction with the indirect design method for buried pipes, and then the improved model was compared with experiment results. An average value of 20 % reduction in CIPP liner thickness was achieved by employing the modified model than the ASTM standard. This study can serve as a database for engineers designing CIPP rehabilitation projects for concrete pipes whose structure has not been completely damaged.

Theoretical and Numerical Study on the Three-Edge Bearing Capacity of Prestressed Concrete Cylinder Pipe

Prestressed Concrete Cylinder Pipe (PCCP) is a composite pipe structure commonly subjected to earth pressure, internal pressure, and ground loads. To confirm the bearing capacity of PCCP by using the in-direct design method, one of the most important experiments is the Three-Edge Bearing (TEB) test. A rational theoretical analysis method and Finite Element Analysis (FEA) are developed in this study because the TEB test is costly and difficult to conduct. The proposed theoretical analysis method and Finite Element (FE) method can be used to calculate the internal force, the displacement, the cracking load, and the bearing capacity of PCCP under the TEB load. In addition, a parametric study is carried out by using the validated theoretical analysis and FEA method. It is found that the concrete strength, the prestressing level, and the radius-to-thickness ratio of the steel cylinder affects the bearing capacity of PCCP under the TEB load. Furthermore, the proposed theoretical analysis method can be used to calculate the bearing capacity of other kinds of rigid pipes under the three-edge bearing load.

Indirect and Direct Design Methods for Design of Reinforced Concrete Pipe

There are currently two acceptable methods by which concrete pipe may be designed per the AASHTO Bridge Design Specifications: the direct design method and the indirect design method. The evaluation of applied load is similar for both methods, however, evaluation of the pipe’s capacity to resist applied load differs between the two methods. The indirect design method uses physical three edge bearing (TEB) testing at the production facility based on a relationship between the forces in the pipe wall in the installed condition compared with forces in the pipe wall from the TEB test. The direct design method follows the conventional design procedure for concrete members where demand versus capacity is determined using load and resistance factors to account for variability in applied loads and resistant capacity of the structure. Because of advances in computer technology, the direct method has become easier to apply than it was in the past. However, the indirect method, which has been used for approximately 70 years, has demonstrated conservatism and is a proven design method. Comparison of similar installations using the two methods has resulted in disagreements with respect to the minimum required reinforcement, however, both methods are adequately conservative, and each may have its place depending on the size and strength of the pipe. This paper presents the fundamental differences between the two design methods and offers some guidance on when to use each of them.

Synthesis, characterization, and properties of a novel aromatic ester-based polybenzoxazine.

Polybenzoxazines with molecular design flexibility have excellent properties by using suitable raw materials. A new benzoxazine monomer terephthalic acid bis-[2-(6-methyl-4H-benzo[e][1,3]oxazin-3-yl)]ethyl ester (TMBE) with bis-ester groups has been synthesized from the simple esterification reaction of terephthaloyl chloride and 2-(6-methyl-4H-benzo[e][1,3]oxazin-3-yl)-ethanol (MB-OH). The chemical structure of TMBE was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H-NMR, 13C-NMR). Polymerization behavior of TMBE was studied by differential scanning calorimetry (DSC) and FT-IR after each cure stage. The cross-linked polybenzoxazine (PTMBE) gave a transparent film through the thermal casting method. The dynamic mechanical analysis of PTMBE showed that the Tg was 110 °C. Thermogravimetric analysis reveals better thermal stability as evidenced by the 5% and 10% weight-loss temperatures (Td5 and Td10) of PTMBE, which were 263 and 289 °C, respectively, with a char yield of 27% at 800 °C. The tensile test of the film revealed that the elongation at break was up to 14.2%.

간접적 참여설계방법을 통한 메모리얼 설계요소 도출

간접적 참여설계방법을 통한 메모리얼 설계요소 도출

Stability Driven Optimal Controller Design for High Quality Images

This note presents an optimal design method to enhance image quality in optical image stabilization (OIS) systems. First of all, performance limitations of conventional methods are shown and secondly, a new design framework based on convex optimization is proposed. The resulting controller essentially stabilizes the closed loop systems because the proposed method is derived from Lyapunov stability. From the test results, it is confirmed that this method reduces the effect of hand vibrations and makes images sharp. Additionally, it is shown that the proposed method is also effective in robot vision and recognition rate of deep neural network (DNN) based traffic signs and pedestrians detection in automotive applications. This note has three main contributions. First, performance limitations of the conventional method are shown. Second, from the relation between sensitivity and complementary sensitivity functions, an indirect design method for performance improvement is proposed, and finally, stability guaranteed optimal design is proposed. Unlike conventional methods, the proposed method does not require addition filters to suppress resonances of the plant and this note highlights phases of the closed loop systems on removing external vibrations.

Economical design of buried concrete pipes subjected to UK standard traffic loading

The British standard (BS) uses the indirect design method to design buried concrete pipes under the effect of traffic load; in this method the laboratory capacity of the pipe is obtained and linked to the field capacity using an empirical factor called the bedding factor. However, the BS design bedding factors have not been rigorously tested. This paper therefore presents a rigorous analysis of the response of buried pipes under the BS traffic loading requirements and tests the robustness of the BS design bedding factors using a validated finite-element model. It was found that the BS bedding factors are overly conservative, with a ratio of calculated values to the design bedding factors ranging from 1·63 to 4·92. This over-conservatism can be attributed to an oversimplification in the BS methodology for calculating the force applied to the pipe. Therefore, new bedding factors have been proposed utilising the evolutionary polynomial regression analysis technique. These bedding factors implicitly account for the error due to the oversimplification in the design force calculation. Hence, more economical and robust designs can be achieved by using the new bedding factors.

Development of a novel model to estimate bedding factors to ensure the economic and robust design of rigid pipes under soil loads

Buried concrete pipes are load bearing structures that need to resist the loads imposed by the surrounding ground. The common approach to design buried concrete pipes is based on an empirical method called the Indirect Design Method, which uses the laboratory capacity of the buried pipe linked to the field capacity using an empirical factor known as the bedding factor. However, limited published studies have investigated this bedding factor or tried to improve the current bedding factor values. Therefore, this study investigated the bending moment and bedding factor for concrete pipes under soil loads by conducting a parametric study investigating the effect of the installation condition, pipe diameter, pipe thickness and backfill height. A validated finite element model has been used for this purpose. The bedding factors obtained from the analyses have been compared with the bedding factors currently adopted by the AASHTO and British Standard (BS) design standards. The results showed that the BS design standard is conservative. In addition, the AASHTO design standard has been shown not to be safe for pipes with a diameter of 0.3 m and becomes more conservative as the diameter increases or the installation quality decreases. Therefore, new bedding factor models have been proposed using the results of the finite element modelling utilising an evolutionary polynomial regression (EPR) method. The paper demonstrates that the new models could be used for the economic and robust design of concrete pipes. The proposed models in this paper have the potential to significantly reduce the costs involved in either construction or maintenance of buried concrete pipes.

An assessment of veracity of filter criteria for earth dams

The core of an earth dam is normally made of clayey base soils and protected by a sandy filter. Designing the filter can be very challenging considering the various criteria established today. This study commences with a review of three prominent criteria referred to in designing filters by the indirect method. No-erosion filter tests are then carried out involving 11 fine-grained, base soil samples with different properties; these are a highly dispersive soil, a soil with a medium to high degree of dispersion, a soil with a low-plasticity silt (ML) classification and a soil with a broad gradation curve. These tests represent the direct method. A comparison of results arising from the two methods shows that designing filters the indirect way, by following established criteria alone, is not always safe. Hence, it is proposed that such designs should be experimentally verified using no-erosion filter tests. Furthermore, instead of following the prevalent criteria in the indirect design method, the perfect filtering method for highly dispersive soils and the reduced particle size distribution method for broadly graded soils are proposed to be used, with merits given for each method. Finally, the paper recommends certain filter criteria from the literature for base soils with a moderate degree of dispersion and an ML classification respectively.

Reliability-Based Structural Design of Concrete Pipes

Concrete pipes are widely used for transferring water in urban infrastructure facilities. The current design standard of concrete pipes in Australia is based on the deterministic indirect-design method. However, there is uncertainty in pipe performance during service life due to assumed design parameters, installation error, changed operational environments, and pipe deterioration. This study aims to assess the reliability of structural performance of concrete pipes at the design stage. The reliability assessment is based on the use of Markov chain theory for modeling pipe deterioration during service life and coefficient of variation for representing uncertainty in design, installation, and operational parameters. The results of a case study show that increasing pipe strength from class 2 as per current design to class 3 as per reliability assessment can significantly reduce the likelihood of structural failure during service life and delay inspection and structural rehabilitation by 10 years. There is a difference in structural deterioration between pipe cohorts, which should be taken into account for reliability-based design.

안정한 종속 BPF의 성능에 관한 연구

This paper is a study on the performance of the stable cascading BPF. There are generally two methods of designing IIR filter, which are a direct method and an indirect one. The indirect design method that is transformed into the BPF by frequency transformation using the prototype analog LPF which is satisfied for designing specifications is applied to this study. As typical prototype analog LPFs, there are the Butterworth filter, the Chebyshev filter and the elliptic filter. In this study, we connect the frequency transformed BPFs (to the cascade form) which have been converted from the stable Butterworth filter and Chebyshev filter. Three classified simulations are conducted in this study, which are the cascading Butterworth BPF Only, the cascading Chebyshev BPF Only and the cascading Butterworth and Chebyshev BPFs. As a result of the simulation, this study shows that a ripple size of the cascading Chebyshev BPF Only is about 1[dB] smaller than that of the cascading Butterworth and Chebyshev BPFs and also the skirt characteristic of the cascading Chebyshev BPF in the transition band is most outstanding and has the widest bandwidth. The result of performance comparison shows the validity of specifications required in the workplace.

Design of macro-synthetic fibre reinforced concrete pipes

This paper presents an experimental campaign in which concrete pipes were manufactured using plastic fibres as the sole reinforcement material. In this regard, it has been demonstrated that the use of plastic fibres is compatible with pipe production systems, and that, when subjected to the crushing test (CT), plastic fibre reinforced pipes yield strength classes that are attractive in terms of the growth of this material in the concrete pipe industry. Moreover, the results obtained from both the characterisation of the material and the mechanical behaviour of the pipes have been used to verify that the Model for the Analysis of Pipes (MAPs) is an appropriate tool for the design of such pipes. Finally, this paper presents a direct design methodology which was used to establish the firsts design tables for fibre reinforced concrete pipes presented in the scientific literature. This methodology can be used to estimate the strength requirements of the fibre reinforced concrete needed to reach the strength classes set out in EN 1916:2002, without having to resort to the CT as an indirect design method.

Cascading Chebyshev filter를 이용한 리플 제거에 관한 연구

This study is focusing on ripple elimination in the band pass filter. There are generally two design methods in IIR filter design, which are a direct method and an indirect one. The indirect design method that designs the digital IIR LPF using the prototype analog LPF is applied to this study. A Butterworth filter and a Chebyshev filter are the typical prototype analog LPFs. This study shows characteristics of the digital IIR LPFs that are transformed from the prototype analog LPFs. The designed Butterworth and Chebyshev IIR LPFs are also designed as the band pass filters by frequency transformation in order to compare with the proposed cascading Chebyshev BPFs. This study shows frequency characteristics between the transformed IIR BPFs and the proposed cascading Chebyshev BPFs as well. The proposed cascading Chebyshev BPF is designed by cascading the different orders of Chebyshev BPFs. The aspect of the cascading filter is offsetting the ripples to descend them while the pass band ripples of the Chebyshev filter are ascending and vice versa. The designed cascading Chebyshev filter shows the flatness and the sharpness, which represent the advantages of Butterworth filter in the pass band and of Chebyshev filter in the transition band respectively. This result verifies the validity of the designed filter.

Experimentation and numerical simulation of steel fibre reinforced concrete pipes

The results concerning on an experimental and a numerical study related to SFRCP are presented. Eighteen pipes with an internal diameter of 600 mm and fibre dosages of 10, 20 and 40 kg/m 3 were manufactured and tested. Some technological aspects were concluded. Likewise, a numerical parameterized model was implemented. With this model, the simulation of the resistant behaviour of SFRCP can be performed. In this sense, the results experimentally obtained were contrasted with those suggested by means MAP reaching very satisfactory correlations. Taking it into account, it could be said that the numerical model is a useful tool for the optimal design of the SFRCP fibre dosages, avoiding the need of the systematic employment of the test as an indirect design method. Consequently, the use of this model would reduce the overall cost of the pipes and would give fibres a boost as a solution for this structural typology.

Recommendations for Design of Reinforced Concrete Pipe

Currently, two methods are available for the design of reinforced concrete pipes: the indirect design method and the direct design method. However, changes to indirect design procedures and proper application of the direct design method may not be well understood by designers. The goal of this work is to present designers with a concise history and major concepts of both methods to facilitate the proper application of either method for reinforced concrete pipe. The development of the indirect design method is given with emphasis on changes in the bedding factor, which is a constant that relates the strength of pipe in the three-edge-bearing test to the strength of pipe in the installed condition. The development of the standard installations and direct design method are presented, and finally a comparison between design results from both methods is made. Recommendations for reinforced concrete pipe design and the proper application of the bedding factor are provided. The direct design method is promoted a...

Long-term monitoring of SIDD Type IV installations

An evaluation of the standard installation direct design (SIDD) prediction method has been undertaken by constructing and monitoring full-scale test beds installed according to SIDD Type IV specifications at four test sites across southern Ontario, Canada. Stresses around the test beds were monitored over a period of 20 months. The internal diameter of the test pipe segments varied from 600 mm to 900 mm; in situ soil conditions ranged from organic clay to sand, and burial depths varied from 1.5 to 3 times the diameter of the installed pipe. All test sections were subjected to frequent heavy traffic loads, representing a worse case loading scenario. Measurements from the 20 month monitoring period were compared with predictions from Ontario Provincial Standards and SIDD specifications. It was concluded that the SIDD method reasonably predicts the stress envelope around a buried rigid pipe installed using the cut-and-cover construction method. The indirect design method currently used by the Ontario Provincial Standards was found to provide an overly conservative prediction of soil stresses at the invert of the pipe. Field measurements also suggest that the value of the horizontal arching factor (HAF) currently recommended by SIDD for Type IV installations is overly conservative and can be increased while maintaining a conservative design approach.Key words: soil, pipe, interaction, rigid, SIDD, monitoring.

Indirect Adaptive Control of Nonlinear Systems Using Takagi-Sugeno Type Fuzzy Logic

An adaptive fuzzy controller is designed using a collection of fuzzy IF-THEN rules. Parameters of membership functions characterizing the linguistic terms in the fuzzy IF-THEN rules are changing according to some adaptive laws, to control a plant to track a reference trajectory. In this paper, an indirect adaptive fuzzy control design method is developed for general higher order nonlinear continuous systems. The Takagi-Sugeno type fuzzy logic system has been used to approximate the controller. It has been proved that the closed-loop system under this adaptive fuzzy controller is globally stable in the sense that all signals involved are bounded. Finally, the indirect adaptive fuzzy controll method has been applied to control an unstable system

Order reduction of 2-D FIR filters with applications

The author develops two algorithms for the order reduction of two-dimensional (2-D) FIR digital filters, which lead to two indirect design methods. Specifically, it is shown how an optimal L/sub 2/ design can be derived as a matrix approximation problem in the Frohenius norm, and how a suboptimal L/sub /spl infin// design can he obtained by solving a matrix approximation problem in the 2-norm using the Davis-Kahan-Weinberger theorem on norm-preserving dilations. A case study is included to demonstrate the usefulness of the proposed methods.