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Glass-based packaging presents unique opportunities for supporting 5G and beyond frequencies. In this work, we present the first broadband characterization results for the electrical properties of Ajinomoto build-up film (ABF) laminated on glass substrates. ABF/glass/ABF-based stack up has been characterized from 20 to 170 GHz. We also report the low-loss performance of ABF/glass/ABF transmission lines. The material stack up consists of a 100- $\mu \text{m}$ -thick EN-A1 glass core from Asahi Glass Company (AGC) with 15- $\mu \text{m}$ ABF GL102 laminated on both sides. Semiadditive process (SAP) has been used to metalize the stack up. A microstrip ring resonator (MRR) method has been used to extract the dielectric constant and loss tangent of the stack up. The dispersive model estimates the dielectric constant of the stack up to be ~4.72 for the entire frequency range with a variance of +0.1. The measured loss tangent values were 0.004, 0.009, and 0.012 at 23, 103, and 140 GHz, respectively. The electrical characterization results with a confidence interval of 95% have been reported. The average insertion loss for coplanar waveguide (CPW) lines in the frequency range was measured to be between 0.055 and 0.50 dB/mm. The average insertion loss for microstrip in the same frequency range was measured to be 0.12–0.62 dB/mm. Along with the good model to hardware correlation, the performance of the transmission lines has been compared with the insertion loss published for other substrate technologies.

This paper describes the demonstration of a low loss substrate (laminated glass) for high-frequency transmission using a dry film build-up material with low loss tangent (Df). This paper also evaluates filter characteristics and dielectric characteristics of the substrate in the mm-Wave band. The advanced low loss dry film build-up material was newly developed, and applicable to high frequency transmission. This material has a Df of 0.0025 at 10 GHz and also exhibits excellent adhesion and electrical reliability required for advanced dielectric materials. In addition, glass was used as a core material in this paper because of its excellent signal transmission characteristics compared to silicon wafers or organic substrates. To demonstrate the benefit of low loss materials for high frequency transmission, passive components for high frequency filter substrates were fabricated using - 6-inch square thin (0.2mm) glass panel with various build-up materials (Material A with a Df of 0.0025, and Material B with a Df 0.0042 at 10 GHz) laminated. Copper wiring patterns on the dielectric layers were fabricated by a semi-additive process (SAP). Circuit patterns with low pass filters and band pass filters were also fabricated. First, transmission characteristics and characteristic impedances were measured to check the electrical performance. The measured lowest transmission loss of < 1.43 dB at 39 GHz were achieved when Material A was applied as the build-up material. Second, biased-highly accelerated stress test (bHAST) was conducted to evaluate the reliability performance of the substrates with two build-up materials, Material A and a conventional material. The test condition was based on the JEDEC level 2 standard. The substrate with Material A retained good insulation properties over 300 hours of bHAST treatment, demonstrating its excellent insulating performance. In summary, Material A has been shown in this paper to exhibit reduced transmission loss in high-frequency filter substrates at millimeter wave frequencies.

Objective: Accelerating the co-simulation method for the design of transmit array (TxArray) coils is studied using equivalent circuit models. Materials and methods: Although the co-simulation method dramatically reduces the complexity of the design of TxArray coils, finding the optimum solution is not trivial since there exist many local minima in the optimization problem. We propose to utilize an equivalent circuit model of the TxArray coil to obtain a proper initial guess for the optimization process of the co-simulation method. To prove the concept, six different TxArray coils (i.e., three degenerate birdcage coils (DBC), two dual-row head coils, and one elliptical body TxArray coil) with two different loading strategies (cylindrical phantom and human head/body model) at 3 T field strength are investigated theoretically; as an example study, an eight-channel head-DBC is constructed using the obtained values. Results: This approach accelerates the design process more than 20-fold for the coils that are investigated in this manuscript. Conclusion: A fast and accurate method for tuning and decoupling of a TxArray coil can be achieved using its equivalent circuit model combined with the co-simulation method.

Linear and nonlinear normal mode motions may provide promising information about the condition of mechanical structures under small and large amplitude vibrations, respectively. In this view, this study investigates the nonlinear dynamics of cracked beams through use of the nonlinear mode motion and extends the crack identification methods that utilize the linear characteristics to nonlinear vibrating structures. At first, the nonlinear normal modes of the intact and cracked beams are calculated by a continuation algorithm. A finite element model of a geometrically nonlinear prismatic beam was created based on crack stress intensity. Subsequently, a method based on normal mode motion and minimization of strain energy, which is valid for linear and nonlinear vibrating beams, was developed as an optimization problem. To this end, hybrid optimization was also used due to its capability in finding global minimum along with its computational efficiency. It was shown that the proposed crack detection technique is applicable to beams vibrating in linear and/or nonlinear regimes and well capable of detecting both crack location and severity.

This work presents characterization of microvia interconnects in D-band frequencies for use as chip-to-package interconnects in Glass Panel Embedded (GPE) packages. Antenna-in-Package based on wafer-level fanout technology have demonstrated superior performance along its small form factor by eliminating wire-bond, assembly, underfill and package substrates. However, epoxy mold compounds, which limit the use of fanout packages at sub-Thz frequencies, do not support the electrical performance, thermal and thermo-mechanical needs of such applications. Embedding chips in glass panels, on the other hand, leverages all benefits of glass substrates and low-loss polymer buildup dielectrics while also mitigating the effects of wire-bond and microbumps for chip-to-package interconnects. In this paper, the design, fabrication, and characterization of these all-copper microvia-like chip-to-package interconnects is presented. These interconnects achieve an average chip-to-package loss of 0.146 dB in D-band and 0.177 dB maximum loss at 170 GHz which is lower than current flip-chip approaches, and our objective is to incorporate such interconnects in the proposed GPE package.

This paper describes the development of a novel dry film-type dielectric material with low loss tangent (D f ) and the demonstration of a low-loss filter substrate using the dielectric material for high-frequency transmission applications. This paper also presents the evaluation results of the small filter characteristics of the substrate in the 28 GHz and 39 GHz 5G millimeter-wave (mmWave) band. We have recently developed a dry film dielectric material with outstanding electrical properties and excellent mechanical properties (Material P). This new material is based on polyphenylene ether (PPE) that has extremely low D f . PPE is commonly known as a thermoplastic polymer, henceforth a new chemical design was applied to modify the polymer structure into a thermosetting polymer. The new dielectric material can be processed at a low temperature about 200°C and is compatible to the standard substrate manufacturing processes, such as semi additive process (SAP). Material characterization revealed that D k /D f of Material P is 3.1 /0.0013 at 10 GHz, and glass transition temperature (T g ) is 200°C. In this work, RF filter performance of the Material P was characterized to demonstrate the benefit of the low loss material. As the reference, the performance of epoxy dielectric was additionally characterized and compared. Electrical characterization of the filter structures showed low transmission losses < 1.0 dB at 28 GHz and < 0.8 dB at 39 GHz with Material P, verifying applicability of the material for high frequency applications.

With the tremendous advances and increasing demand in 5G communications, the low-loss performance of RF device components becomes more critical. Two parameters that have significant impact on the low-loss RF performance are lower circuit conductor loss and dielectric loss of the build-up materials. Therefore, this study is focused on the loss tangent (D f ) of the dielectric build-up material and demonstration of its electrical reliability with a low-loss substrate for high-frequency transmission. This newly developed advanced low-loss dry film build-up material exhibits a D f values of < 0.003 at 39 GHz and is applicable to high frequency transmission. This build-up material also exhibits excellent electrical reliability required for advanced dielectric materials. For evaluation of the filter characteristics in the mm Wave band, a substrate with filter circuit structures was fabricated using the low loss dielectric material. Transmission characteristics of the filters were measured and demonstrated to have a minimum transmission loss of less than 1.18 dB at 39 GHz.

The seismic assessment of heritage buildings has great importance in terms of preservation and sustainability due to their priceless inheritance. In general, the material properties used in...

Glass is a promising packaging and substrate material for high frequency applications. In this paper we provide the first results on the performance of transmission lines on polymer films laminated on glass substrates up to 170GHz. To benchmark the performance our stack up consists of 100um thick glass panel (AGC ENA1) with 15um thick build-up polymer (ABF GL102) laminated on both sides. Semi-additive processes (SAP) are employed to metallize the polymers. Coplanar Waveguide (Lines) have been designed and measured in a wide frequency range from 40GHz to 170GHz. We also present the insertion loss of microstrip lines in W-band (75GHz to 110GHz). In addition, for the first time, we present the characterization of electrical parameters (dielectric constant and loss tangent) of glass and polymer build up film-based stack up for W band (75GHz to 110GHz). For the extraction of dielectric constant and loss tangent of the proposed stack up, microstrip ring resonator (MRR) method is used. The dielectric constant of the presented stack up remains stable around 4.6 for the entire band while loss tangent varies from 0.004 to 0.008 from 75GHz to 100GHz. The average insertion loss for CPW lines at 40GHz,110GHz and 170GHz were measured to be 0.085dB/mm, 0.21dB/mm and 0.275dB/mm respectively. The measured insertion loss at 110GHz for microstrip line is 0.23dB/mm. The results show good and stable electrical performance of the glass-based stack up up to 170GHz and show its potential for utilization in designing high performance passives and packages for the development of future wireless generations.

This study examines the seismic behavior of the minaret of the well-known historical structure “Sultan Ahmed Mosque” under strong earthquake motion. Despite their slenderness and height, minarets are towers with well-established earthquake resistance. In general, these structures were constructed adjacent to the main structure and/or its components. Hence, it is expected that the dynamic behavior of the minarets is influenced by the dynamic characteristics of the adjacent structures as well as the contact conditions. In the presented study, the dynamic behavior of the M6 minaret of the Sultan Ahmed Mosque, which is in contact with the portico that surrounds the courtyard of the mosque, is considered. Ambient vibration tests were conducted on site in order to identify the individual and coupled vibration modes of the minaret and the portico. A finite/discrete model was developed and seismic analysis was carried out. The comparative study reveals considerable differences in responses of different mo...

By virtue of the advanced numerical techniques and in-situ measurements, it is now possible to develop suitable methodologies to be used in the decision making on the rehabilitation of the historical and monumental structures. In this sense, this article presents suitable approaches to support decision-making process. Discrete- and continuum-based finite element modeling strategies that are to be used in the seismic assessment of masonry structures are investigated. The calibration of finite element models by the use of available experimental data is also introduced. In the calibration of discrete models, a finite element model updating (FEMU) procedure that considers the stiffness of contact between adjacent stone units was used. The time history seismic analysis of the updated models were finally carried out using both implicit and explicit time integration schemes in order to introduce the differences in the prospective modelling approaches. First, adopted strategy was verified on a simulated c...

The paper deals with the seismic behavior and retrofitting of a historical masonry building called Treasury Building of Hagia Sophia (Skeuophylakion: a building where eucharistic elements were collected and prepared for services) which has experienced lots of earthquakes since it was constructed in 361 and suffered structural damage since then. A detailed finite element (FE) model of the treasure building was created based on the elaborate technical drawings of the structure. A macro modeling approach was adopted and equivalent material parameters were obtained from in-situ tests and the calibration of the FE model was used as the input of the model. Four different models were created considering both the physical and the geometrical nonlinearities in order to understand the seismic behavior of the existing structure and also to account for several retrofit effects on the seismic behavior of the structure. The treasure building was analyzed under very strong earthquake ground motions it might have been exposed during its life time to understand its response and the cause of the observed manner and paths of the observed cracks. It was found out that the plastic strain distribution obtained from the seismic analyses of the first two models and those of the significant cracks observed in situ on the dome and at the tips of arcs are completely compatible. Hence, it was concluded that these cracks are due to the earthquakes occurred until now. The results of seismic analysis of the third and fourth models show that the use of belts (rings) at the location close to the top elevation of arches of windows for retrofitting the structure improves the performance and seismic behavior of the structure considerably.

The paper deals with the seismic behavior of a masonry memorial which experienced two earthquakes in one year and suffered serious structural damage. The memorial was first built in 1992 to commemorate the soldiers died in great Gallipoli war, which was held between Ottoman Empire and Allied countries in Canakkale peninsula a hundred years ago. In 2013, it was replaced with the existing one using cut stone masonry units with mortar as bindings. The site investigation has revealed permanent residual damages and failure of material in some specific locations at the uppermost segment of the memorial occurred during the successive earthquake events. In this study, some flaws in the engineering design of the memorial are addressed, which are related to the lateral stiffness distribution along the structure’s height. In addition, the material tests conducted on the specimens taken from the memorial revealed that the material strength is too poor. Ambient vibration tests were also conducted on site in order to identify the modal parameters of the memorial and compare with the results of initial finite element model. Finally, a finite-discrete element model of the memorial was created and analyzed under Canakkale earthquakes as well as a more intense earthquake occurred in Duzce/Turkey in 1999. The seismic behavior of the original and the existing structure are investigated and compared. Additionally, a retrofitted model of the memorial by using lead bars which tie the masonry units vertically and/or horizontally was created and analyzed. The results show that the performance of the memorial retrofitted by the lead bars is much better than the initial model. In addition, the earthquake resistance of the original structure which has a more appropriate lateral stiffness distribution is higher.

This paper presents challenges, opportunities and approaches for packaging at THz frequencies. The two approaches discussed here are laminate based approach and Glass Panel Embedding (GPE). Laminate based solutions provide for low cost and reasonable performance but have challenges in terms of supporting low profile. This approach can be made effective and efficient by introducing air cavities in the laminate stack up to reduce losses, provided reliability can be addressed. Currently there are challenges in precisely structured air cavity fabrication for multi-layered substrates. Glass Panel Embedding (GPE) is a promising packaging approach for THz applications owing to its excellent dimensional stability and low profile. The GPE packaging approach using multiple dies can help support cavities, heterogeneous ICs such as PA and beamformer, interconnects, integrated phased array antennas and passives along with a robust thermal solution.

Pounding tuned mass dampers (PTMD), which relies on impact to dissipate vibration energy, have shown remarkable performance in suppressing structural vibrations with its modest design. However, the optimum design of PTMDs is computationally expensive due to non-smooth contact-impact behavior. This study provides a computationally efficient approach to determine the optimal parameters of single-sided PTMDs used in vibration control of structural systems. An optimization strategy is used to minimize the maximum response of the controlled structure. As is well-known, the calculation of the dynamic response of a structure could be cumbersome when conventional time-stepping techniques are used in each iteration of the optimization routine. Hence, an exact analytical solution of the steady-state vibration is used to calculate the response for different excitation frequencies, which substantially decreases the computational burden. The adopted method is computationally very inexpensive with respect to the conventional time-stepping techniques used to solve the nonlinear equations of motion to obtain response quantities. The exact solution only requires the solution of the system of five nonlinear equations in order to evaluate the steady-state response per each excitation frequency of harmonic force. A four-storey shear building is used to evaluate the optimally-tuned PTMD by the proposed procedure. In addition, simplified design equations for the coefficient of restitution and frequency ratio are provided using curve and surface fitting for preliminary design. It was shown that the effect of damping ratio of the primary structure on the optimal coefficient of restitution value is not considerable, while it has significant influence on the optimal frequency ratio. It was also realized that the objective function used in optimum parameter design has only one local optimum, which is suitable for the application of gradient-based optimization methods.

Minarets are almost the inevitable part of Mosques in Islam and according to some, from a philosophical point of view, today they symbolize the spiritual elevation of man towards God. Due to slenderness, minarets are susceptible to earthquakes and wind loads. They are mostly built in a masonry style by using cut limestone blocks or occasionally by using bricks. In this study, one minaret (M1 Minaret) of one of the charmest mosques of Turkey, Sultan Ahmed Mosque, popularly known as Blue Mosque, built between 1609 and 1616 on the order of Sultan Ahmed by the architect Mehmet Agha is investigated under some registered earthquake loads. According to historical records, a great earthquake hit Istanbul and/or its close proximity approximately every 250 years. Ottomans tackled with the problem of building earthquake resistant, slender minarets by starting to use forged iron connectors with lead as a filler to fix them to the upper and lower and to adjacent stones instead of using traditional mortar only. Thus, the discrete stones are able to transfer tensile forces in some sense. This study investigates the contribution of lead to the energy absorption capacity of the minaret under extensive earthquakes occurred in the region. By using the software ANSYS/LS-DYNA in modelling and investigating the minaret nonlinearly, it is found out that under very big recorded earthquakes, the connectors of vertical cast iron-lead mechanism play very important role and help to keep the structure safe.

Developments and advances in experimental technologies providing useful data make it possible to identify civil engineering structures and to obtain a more reliable model characterizing the existing condition for decision making. Analytical models such as Finite Element (FE) models, which are calibrated using structural health monitoring (SHM) data, better represent the existing structures' behavior under different loading conditions. However, the SHM data should include sufficient information about the structural parameters to be identified. In this study, a novel methodology is proposed in order to determine the optimum sensor configuration which provides adequate data for structural identification (St-Id). The success of the St-Id is investigated in a comparative fashion by comparing the model parameters calibrated using different sensor configurations. Uncertainties both in the mathematical model and the experimental data are taken into account using the fuzzy number concept. A so-called inverse fuzzy arithmetic technique is used to quantify the uncertainties in the updated parameters. The proximity of linkage values, which are the product of cluster analysis, is used to determine the optimal sensor configuration. The optimal sensor configuration is then verified by using the relative amount of uncertainty in the updating parameters resulting from the inverse propagation of the uncertainties. A hybrid evolutionary optimization algorithm is also proposed in order to efficiently minimize an objective function that consists of differences between the fuzzy experimental measurements and the analytical data. Genetic Algorithms (GA) and Harmony Search (HS) algorithm are combined to enhance the efficiency and the robustness of the optimization process. An analytical benchmark bridge structure developed for bridge health monitoring studies is used as the test structure to verify the proposed methodologies. Three different cases including the undamaged and the damage cases are considered. It has been shown that there is no significant difference between the St-Id results obtained by using a dense sensor configuration and the optimum configuration obtained by the proposed method in terms of accuracy.

A fuzzy finite element model updating (FFEMU) method is presented in this study for the damage detection problem. The uncertainty caused by the measurement noise in modal parameters is described by fuzzy numbers. Inverse analysis is formulated as a constrained optimization problem at each @a-cut level. Membership functions of each updating parameter which correspond to reduction in bending stiffness of the finite elements is determined by minimizing an objective function using a hybrid version of genetic algorithms (GA) and particle swarm optimization method (PSO) which is very efficient in terms of accuracy and robustness. Practical evaluation of the approximate bounds of the interval modal parameters in FFEMU iterations is addressed. A probabilistic analysis is performed using Monte Carlo simulation (MCS) and the results are compared with presented FFEMU method. It is apparent from numerical simulations that the proposed method is well capable in finding the membership functions of the updating parameters within reasonable accuracy. It is also shown that the results obtained by FFEMU are in good agreement with the MCS results while FFEMU is not as computationally expensive as the MCS method. Nevertheless, the proposed FFEMU do not required derivatives of the objective function like existing methods except in the deterministic case.

This article aims to investigate the effect of uncertainties on the predicted response of structures using updated finite-element models (FEMs). Modeling uncertainties are quantified by fuz...

Analytical and numerical models that simulate the physical processes inevitably contain errors due to the mathematical simplifications and the lack of knowledge about the physical parameters that control the actual behavior. In this sense, parametric identification of civil engineering structures using uncertain numerical models should be subject to a particular interest in terms of accuracy and reliability of identified models. In this study, model uncertainties are modeled by fuzzy numbers and quantified using fuzzy model updating approach. In order to find the possible variation range of the response parameters (e.g. natural frequencies, mode shapes and strains) using uncertain finite element model, successive updating is employed. A simplified approach is proposed in order to facilitate the time consuming successive model updating phase. The identified variation range of the response parameters is employed to construct the fuzzy membership functions for each response parameter. Finally, fuzzy finite element model updating method (FFEMU) is used to obtain the membership functions of the model parameters. Different sets of model parameters are chosen to represent different models in terms of accuracy and these parameters are identified in the same way to investigate the model complexity. A two span laboratory grid structure developed for simulating bridge structures is used to validate and demonstrate the proposed approaches. The results show that the proposed approaches can efficiently be utilized to quantify the modeling uncertainties for more realizable and quantitative condition assessment and decision making purposes.

There is a wide variety of existing Genetic Algorithms (GA) operators and parameters in the literature. However, there is no unique technique that shows the best performance for different classes of optimization problems. Hence, the evaluation of these operators and parameters, which influence the effectiveness of the search process, must be carried out on a problem basis. This paper presents a comparison for the influence of GA operators and parameters on the performance of the damage identification problem using the finite element model updating method (FEMU). The damage is defined as reduction in bending rigidity of the finite elements of a reinforced concrete beam. A certain damage scenario is adopted and identified using different GA operators by minimizing the differences between experimental and analytical modal parameters. In this study, different selection, crossover and mutation operators are compared with each other based on the reliability, accuracy and efficiency criteria. The exploration and exploitation capabilities of different operators are evaluated. Also a comparison is carried out for the parallel and sequential GAs with different population sizes and the effect of the multiple use of some crossover operators is investigated. The results show that the roulettewheel selection technique together with real valued encoding gives the best results. It is also apparent that the Non-uniform Mutation as well as Parent Centric Normal Crossover can be confidently used in the damage identification problem. Nevertheless the parallel GAs increases both computation speed and the efficiency of the method.

Finite element (FE) model updating belongs to the class of inverse problems in mechanics and is a constrained optimization problem. In FE model updating, the difference between the modal parameters (the frequencies, damping ratios and the mode shapes) obtained from the FE model of the structure and those from the vibration measurements are minimized within an optimization algorithm. The design variables of the optimization problem are the stiffness reduction factors, which represent the damage. In this study, the Genetic Algorithms (GA), the Parallel GA, the local search algorithms, the Trust Region Gauss Newton, the Sequential Quadratic Programming, the Levenberg–Marquardt Techniques and the hybrid versions of these methods are applied within the FE Model Updating Technique for updating the Young's modulus of different FEs of a reinforced concrete beam. Different damage scenarios and different noise levels are taken into account. The results of the study show that the local search algorithms cannot detect, locate and quantify damage in reinforced concrete beam type structures while the GA together with the hybrid and the parallel versions detect, localize and identify the damage very accurately. It is apparent that the hybrid GA & Trust Region Gauss Newton Technique is best in terms of the computation speed as well as accuracy.