Main Structure Design Research Articles

CEO activism is not equal to CEO activism: a typology of executives' political statements

PurposeWhen CEOs are publicly weighing in on sociopolitical debates, this is known as CEO activism. The steadily growing number of such statements made in recent years has been subject to a flourishing academic debate. This field offers first profound findings from observational studies. However, the discussion of CEO activism lacks a thorough theoretical grounding, such as a shared concept accounting for the heterogeneity of sociopolitical incidents. Thus, the aim of this paper is to provide an archetypal framework for CEO activism.Design/methodology/approachThe authors used a multiple case study approach on 145 activism cases stated by CEOs and found seven distinct statement archetypes.FindingsThe study identifies four main structural design elements accounting for the heterogeneity of activism, i.e. the addressed meta-category of the statement, the targeted outcome, the used tonality and the orientation of the CEOs’ positions. Further, the authors found seven distinguishable archetypes of CEO activism statements: “Climate Alerts”, “Economy Visions”, “Political Comments”, “Self-reflections and Social Concerns”, “Tech Designs”, “Unclouded Evaluations” and “Descriptive Explanations”.Research limitations/implicationsThis typology classifies the heterogeneity of CEO activism. It will enable the analysis of interrelationships, mechanisms and motivations on a differentiated level and raise the comprehensibility of research-results.Practical implicationsThe framework supports executives in understanding the heterogeneity of CEO activism and to analyse personality-fits.Originality/valueTo the authors’ knowledge, this marks the first conceptualisation of activism developed cross-thematically. The work supports further theory-building on CEO activism.

High-Rise Timber Offices: Main Architectural and Structural Design Parameters

High-Rise Timber Offices: Main Architectural and Structural Design Parameters

Effects of Thermal-Moisture Coupled Field on Delamination Behavior of Electronic Packaging

Abstract Delamination failure is one of the most prevalent and serious reliability issues in micro-electronic packaging. To understand this phenomenon further, this study constructs an experimental test system consisting of a double cantilever beam (DCB) fixture, an MTS-Acumen microforce tester, and a temperature and humidity controller. The system is employed to investigate the effects of coupled moisture-thermal loading on the critical strain energy release rate (SERR) at the epoxy molding compound (EMC)/Cu leadframe (LF) interface of a very thin quad flat no-lead package (WQFN) assembly. A three-dimensional computational model with hygro-thermal loading conditions is developed to evaluate the moisture diffusion, thermal stress, and integrated stress of a multichip WQFN package under typical processing conditions and precondition tests. The validated simulation model is then applied with the virtual crack closure technique (VCCT) to investigate the fracture behavior at the EMC/Cu LF interface in the WQFN package. The effects of three design parameters on the SERR performance of the package are identified through a parametric analysis. Finally, a Genetic Algorithm (GA) optimization method is employed to examine the effects of the main structural design parameters of the WQFN package on its delamination reliability. The results are used to determine the optimal packaging design that minimizes the SERR and hence enhances the package reliability.

Analysis of the Main Architectural and Structural Design Considerations in Tall Timber Buildings

Tall timber buildings represent an emerging and highly promising sector due to their potential to yield significant environmental and economic advantages throughout their entire life cycles. Nonetheless, the existing body of literature lacks a comprehensive exploration of the primary architectural and structural design considerations for such sustainable towers. To address this gap and to enhance our understanding of emerging global trends, this study scrutinized data from 49 tall timber building case studies from around the world. The key findings revealed the following: (1) Europe stood out as the region boasting the highest number of tall timber buildings, with North America and Australia following behind; (2) residential applications were the most preferred function for tall timber buildings; (3) central cores were the predominant choice for core configuration; (4) prismatic forms were the most prevalent design preferences; (5) composite materials were notably widespread, with timber and concrete combinations being the most prominent; (6) structural systems primarily featured shear–frame systems, especially shear-walled frames. By unveiling these contemporary characteristics of tall timber buildings, this research is expected to provide valuable insights to architects, aiding and guiding them in the design and execution of future sustainable projects in this field.

Nonlinear analysis of the impact of openings on punching shear strength

AbstractReinforced concrete flat slab projects usually require openings close to the columns for electrical and hydraulic installations. Since such openings reduce the punching shear of slabs, a comprehensive study is needed. In this paper, numerical models of slabs tested in literature were elaborated upon, using the commercial software in finite elements DIANA. The physical nonlinearity of the materials was considered. After the calibration and validation of the numerical parameters related to concrete and reinforcement, 62 numerical models were created for performing a parametric analysis. The numerical analysis aimed to study the effect of openings close to the columns and verify the punching resistance reduction. In this parametric study, the main variables were the compressive strength of the concrete, the bending reinforcement ratio, the number of openings, and the distance from the openings to the column's face. Finally, the numerical results obtained were compared with the punching strength values provided by the main structural design codes, viz., NBR 6118 (2014), Eurocode 2 (2004), ACI 318 (2019), fib Model Code (2010), and the next generation of Eurocode 2, which are constantly questioned in academic papers regarding their safety.

Design and test of a DCT curved superconducting dipole magnet for ion-therapy

A curved superconducting dipole magnet based on Discrete Canted-Cosine-Theta (DCT) coil with magnetic field of 2.9 T, bend radius of 0.8 m, and bend angle of 90° for next- generation of compact ion-therapy treatment facility has been designed and tested. The curved dipole is comprised of eight layers of DCT coils embedded in the formers wound with NbTi wires, featuring compact ends and higher excitation efficiency. This paper presented the main mechanical structure design, analysis, and measurements of the curved DCT magnet. Based on the finite element method (FEM) model with ANSYS, a detailed analysis of the DCT magnet mechanical behavior during cool-down and excitation has been studied. Finally, the magnetic field and strain measurements are measured from a cryogenic test bath cooled with liquid helium, during which the magnet reached 70% of the expected goal. The reason for magnet failure based on the strain measurement results is also reported in this paper.

Investigation on Seismic Performance of the Fully Assembled Steel Frame Applying Beam-Column Joints with Replaceable Energy-Dissipating Elements

Based on the application of a beam-column joint with replaceable energy-dissipating elements and hinged beam-column proposed by the author, the seismic performance of a fully assembled steel frame with this joint was investigated in this paper. Through two projects of a traditional steel frame (TSF) and an assembled steel frame applying beam-column joints with replaceable energy-dissipating elements (ASFWREE) and their numerical simulation calculation by SAP2000, the main structural design indicators such as natural vibration period, period ratio, mass participation coefficient, base shear force, inter-story displacement angle, rigid-weight ratio, and shear-weight ratio of two frames under frequent earthquake, and their influence factors were compared and analyzed. By carrying out the elastic–plastic dynamic time–history analysis of two projects under a rare earthquake, the maximum inter-story displacement angle, base shear force, stiffness between floors, maximum vertex displacement, and the occurrence sequence and distribution of plastic hinges of the two items were compared. The results show that the deformation of ASFWREE had the characteristics of the shear deformation of TSF and the deviation of the natural vibration period was less than 5% when the ratio of the linear stiffness of the energy-dissipating element to the steel beam was approximately 0.8, the ratio of horizontal length to span was about 0.25, which was close to the strength grade of the steel beam. The seismic performance under the rare earthquake was close to or higher to that of the TSF, can ensure that the beam and column are not damaged, and the structure does not collapse. The failure mode of the ASFWREE is consistent with the experimental research of the beam-column joints.

Research progress and prospect of insulation characteristics of HVDC converter transformer bushing

The paper mainly analyzes the development of the high voltage bushing is closely related to the development of power industry. With the gradual rise of the voltage level in power industry, bushing has experienced the development process from low voltage, high voltage, ultra-high voltage to ultra-high voltage. In order to meet operation requirements under the different voltage levels, the pure porcelain bushing, metal shielded bushing and capacitive bushing have also appeared in the bushing body structure, and the core material has gradually changed from the oil impregnated paper and the adhesive paper to adhesive impregnated paper. In the process of the continuous development of bushing structure and main insulation materials, the research on the high-voltage bushing mainly focuses on the material performance test of bushing, the improvement of the main insulation structure design method, and the simulation analysis of bushing voltage and heat sharing.

Design of Venturi-Type Fertilizer Injectors to Low-Pressure Irrigation Systems

Twenty prototypes of Venturi-type fertilizer injectors for low-pressure agricultural irrigation systems were designed based on functional hydraulic pressure head and variation of their structural designs. These prototypes were modelled in three dimensions (3D) and evaluated using simulation through Computational Fluid Dynamics software (CFD). The main structural design characteristics come from a real necessity to complement an low pressure multigate irrigation system project named in Spanish “El Manzano” (The Apple tree) and bring it the fertigation possibility. The aim of this research was to select the best prototype, in order to identify the convergent and divergent angles, throat diameter and hydraulic pressure head to efficiently produce a Venturi-type injector for use in gated-irrigation pipe irrigation systems for use in a future in “El Manzano” project. As a result of the simulations, the physical characteristics of the injector were defined. The inlet and outlet diameters should be 152.4 mm, the throat diameter 76.2 mm and the suction diameter of 50.8 mm. The convergent and divergent angles showing most improved performances were 7.5 and 10°, respectively. This methodology can be used to construct Venturi-type fertilizer injectors for low-pressure gated-pipe agricultural irrigation systems, which, on one side, can reduce significantly the fertilizer application costs and, on the other side, the fertilizer management efficiency can be also improve considerably to save water resources. There is relatively very little experience in using this type of fertilizer injectors in low-pressure irrigation systems.

Contemporary tall residential timber buildings: what are the main architectural and structural design considerations?

PurposeThis study examined data from 13 international tall residential timber building case studies to increase our understanding of the emerging global trends.Design/methodology/approachData were collected through literature surveys and case studies to examine the architectural, structural and constructional points of view to contribute to knowledge about the increasing high-rise timber constructions globally.FindingsThe main findings of this study indicated that: (1) central cores were the most preferred type 10 of core arrangements; (2) frequent use of prismatic forms with rectilinear plans and regular extrusions were identified; (3) the floor-to-floor heights range between 2.81 and 3.30 m with an average of 3 m; (4) the dominance of massive timber use over hybrid construction was observed; (5) the most used structural system was the shear wall system; (6) generally, fire resistance in primary and secondary structural elements exceeded the minimum values specified in the building codes; (7) the reference sound insulation values used for airborne and impact sounds had an average of 50 and 56 dB, respectively.Originality/valueThere is no study in the literature that comprehensively examines the main architectural and structural design considerations of contemporary tall residential timber buildings.

Thermal and Mechanical Characterization of 2.5-D and Fan-Out Chip on Substrate Chip-First and Chip-Last Packages

Heterogeneous integration technology makes possible the integration of multiple separately manufactured components into a single higher level assembly with enhanced functionality and improved operating characteristics. Various types of advanced heterogeneous packages are available, including 2.5-D integrated circuit (IC), fan-out chip on substrate (FOCoS) chip-first, and FOCoS chip-last. This study constructs a nonlinear simulation technique (3-D simulation model) to explore the warpage, extreme low-<inline-formula> <tex-math notation="LaTeX">$k$ </tex-math></inline-formula> (ELK) interconnect stress, redistribution layer (RDL) trace stress, and board-level solder joint reliability of all three packages. The validity of the simulation model is confirmed by comparing the numerical results for the in-plane dimensional change of an FOCoS chip-last package with the experimental observations over the temperature range of 30 &#x00B0;C&#x2013;260 &#x00B0;C. The thermal performance (i.e., junction-to-ambient thermal resistance) of the three packages is then examined and compared. Finally, <inline-formula> <tex-math notation="LaTeX">$2^{5}$ </tex-math></inline-formula> factorial designs with the analysis of variance (ANOVA) are conducted to examine the effects of the main structural design parameters of the FOCoS chip-last package on its thermomechanical reliability under typical thermal loading conditions. It is shown that a thinner polyimide (PI) layer is beneficial in improving the package reliability by minimizing the coefficient of temperature expansion (CTE) mismatch between the PI layer and the RDL trace, respectively.

Modeling and analysis of hybrid energy absorption devices for aircraft structures

The design of structures according to impact protection or crashworthiness criteria aims for maximum kinetic energy dissipation through progressive component collapse, with the ultimate goal of minimizing the acceleration peaks suffered by occupants. One of the common trends for reducing accelerations in aircraft structures is that of including collapsible absorbers within the main structural design. This communication focuses on the crushing analysis through numerical simulation of thin-walled hybrid energy absorbers. These absorbers combine a confining metallic tube with a core made from composite materials and high-density structural foam. The components are characterized with different crashworthiness metrics, including the energy absorbed by the device or the peak force during the crushing process. The usage of hybrid elements delivers a significant enhancement compared to the single-component counterparts, improving the structural behavior of the aircraft under impact loading and better protecting the occupants. Results show that, at the component level, the usage of inner reinforcements modifies the collapse mechanism of the specimen and increases the specific energy absorption of the device, mainly rooted in the interaction effect between the core and the confining tube.&nbsp;

Space Efficiency in Contemporary Supertall Residential Buildings

Space efficiency is one of the most important design considerations in any tall building, in terms of making the project viable. This parameter becomes more critical in supertall (300 m+) residential towers, to make the project attractive by offering the maximum usage area for dwellers. This study analyzed the space efficiency in contemporary supertall residential buildings. Data was collected from 27 buildings, using a literature survey and a case study method, to examine space efficiency and the main architectural and structural design considerations affecting it. The results of this research highlighted that: (1) central core was the most common type of design parameter; (2) prismatic forms were the most preferred building forms; (3) the frequent use of reinforced concrete was identified, compared to steel and composite; (4) the most common structural system was an outriggered frame system; (5) the space efficiency decreased as the building height increased, in which core planning played a critical role; (6) when building form groups were compared among themselves, no significant difference was found between their effects on space efficiency, and similar results were valid for structural systems. It is believed that this study will help and direct architects in the design and implementation of supertall residential projects.

Research on the Kinematic Compatibility of Position Solution of a Four-DOFs Mechanical Structure Mechanism

Upper extremity rehabilitation exoskeletons are the key devices for stroke patients with movement function disorders. Based on the configuration synthesis and optimum principles of 4-DOFs upper limb exoskeleton mechanisms, an exoskeleton mechanism compatible with upper limb were presented. When the exoskeleton was worn to the upper extremity, a kinematic chain with two closed loops was formed. Moreover, the kinematic equations of the chain were established and a position solution method was addressed. Based on the presented position solution, the kinematic characteristics during eating movement were investigate. The conclusion suggested that the exoskeleton was applied to the upper extremity rehabilitation and can be applied as main structural design parameters for the presented exoskeleton.

Chirped-apodized Thue-Morse quasiperiodic structures for multichannel optical dispersion compensation

Nowadays, optical data transmission systems are significantly involved in telecommunication networks. Particularly, hundreds of data channels can be sent concurrently over a single optical fiber through dense wavelength division multiplexing (DWDM) and optical time division multiplexing technologies. Nevertheless, dispersion imposes main limitations for having high capacity systems with high transmission rates. This paper suggests a new dispersion compensating scheme by introducing one-dimensional chirped and apodized Thue-Morse quasiperiodic structures. Numerical investigations of the dispersion features of the proposed structure is presented. According to the acquired relatively smooth and negative slope group delay (GD) along with corresponding negative constant group velocity dispersion (GVD) of the reflection bands, it would be possible to apply the suggested structure in an efficient way in DWDM applications for multiband dispersion compensation in optical communication systems. The designed multilayer structure with short physical length and ultrahigh negative dispersion coefficient and with the free spectral range (FSR) of about 0.8 nm meets the International Telecommunication Union-Telecommunication Standardization (ITU-T) Sector requirements. Besides, the impact of main structural design parameters on the spectral features of the suggested system are presented in this paper.

Thermal Performance and Insulation Structure Design of ± 400kV Valve Side Bushing of Converter

The design features of inner and outer insulation structure of valve side bushing of ± 400kV converter transformer are representative. Its main insulation structure type and design method are basically consistent with those of ± 800kV converter transformer valve side bushing in China, but its design margin is lower than that of UHV converter transformer bushing, and the valve side bushing of ± 400kV converter transformer is used more in converter valve hall, so its insulation structure design and engineering should be It is necessary to analyze and discuss the insulation structure design of valve side bushing of ± 400kV converter transformer. In this paper, ± 400kV converter transformer valve side bushing insulation accident is analyzed in detail, from which the specific causes of insulation failure are summarized, providing reference for the design of internal and external insulation structure of converter transformer bushing. Based on this, this paper first analyzes the heating mechanism of the double guide rod structure of the converter bushing, gives the design size of the double guide rod structure from the theoretical analysis point of view, further optimizes the core insulation structure of the converter bushing, and gives the external insulation design scheme of the converter bushing from the perspective of internal and external insulation coordination, and checks and calculates the overall electric field distribution The radial electric field strength is controlled at 3.11kV/mm under working voltage and 0.51kV/mm under power frequency withstand voltage, which meet the requirements of electric field strength control in the design of ± 400kV converter bushing. Furthermore, the valve side bushing of the developed ± 400kV converter transformer is tested, and typical type tests such as power frequency dry withstand voltage test and partial discharge measurement, lightning impulse dry withstand voltage test and partial discharge measurement and temperature rise test are passed. The research results of this paper theoretically give the control requirements for the field strength design of the valve side bushing of converter transformer, and optimize the design size of its double guide rod structure, and develop a prototype to prove the effectiveness and reliability of the theoretical analysis. The above research results have good theoretical guidance value and practical significance for the insulation structure design and operation state maintenance of valve side bushing of ± 400 kV converter transformer.

Institutional Analysis of Multifunctional Fruit Picker

Fruit is a major pillar industry for economic development in many regions of China, and it is the third largest crop after crops and vegetables. However, the level of mechanization of fruit harvesting is still in its infancy, and most of them are mainly manual harvesting. The workload is heavy, the picking intensity is not easy to grasp, and it is easy to damage the fruit. Based on the research of fruit picking devices at home and abroad and field visits to orchards, this paper draws up design schemes and conducts main structural design and parameter calculations. The product can achieve 10 kinds of picking work, such as fruit apple, peach, orange, litchi. This greatly reduces the labor intensity of the picking work, improves the efficiency of the picking operation, and provides reference design experience for the fruit picking industry.

Optimización Simultánea del Diseño Conceptual de Procesos y Layout de Planta Considerando el Riesgo Tecnológico

En este trabajo se presentan brevemente los avances y resultados desarrollados en el marco de la tesis doctoral titulada “Metodología para la Optimización de Layout y Síntesis de Procesos Considerando el Riesgo Tecnológico”. A través de la misma se pretende desarrollar un algoritmo eficiente que permita la obtención de la distribución óptima de las unidades de proceso y de los departamentos presentes en el complejo industrial bajo la consideración de la filosofía de diseño inherentemente seguro, incluyendo las principales restricciones de diseño estructural. Para la implementación de tal algoritmo, se han desarrollado modelos de optimización que permiten vincular la toma de decisiones en la etapa del diseño conceptual y del diseño del layout a través de la contemplación de las aristas comunes entre ambas etapas, considerando tanto la vulnerabilidad del interior de la planta como la del entorno (viviendas, escuelas, hospitales, etc.). Esta vinculación se llevó a cabo mediante el desarrollo de modelos reducidos para la evaluación del impacto ante distintos eventos accidentales.

Impact of COVID-19 on the Institutional Education System and its Associated Students in Bangladesh

Aim: The effect of the current COVID-19 pandemic on the education system of Bangladesh and its possible solution is the focus of the present study.&#x0D; Design: The study employed a descriptive survey research design.&#x0D; Place and Duration of Study: The study was conducted through all the districts of Bangladesh from 8 March (2020) to 30 July (2020) accordingly.&#x0D; Methodology: Descriptive survey with the interactive interview via online in the pandemic area and offline field works for collecting data in possible places were the main structural design of this research.&#x0D; Results: The COVID-19 has affected worldwide education sectors by shutting down many institutes and temporarily pushing the majority of students out of school. Most countries have temporarily closed their educational institutions to control the COVID-19 pandemic. In Bangladesh, near 40 million students are now out of school, until the epidemic returns to normal. Besides this universal disruption, out-school learning deprivation varies depending on the socio-economic status of the mass population, their access to technology, parental capabilities, and so on. Most countries are using online or satellite television platforms to deliver education during the pandemic, which is not enough to meet the contrasting levels. Although, developed countries (first and second world) are making good strides with online teaching while struggles are seen in rest (third-world countries). This article highlights how COVID-19 is affecting the education sector and students in Bangladesh. Undoubtedly, the most immediate impact of the Covid-19 on students of Bangladesh is abruptions in learning opportunities with multiple other aspects. Despite earnest government attempts, COVID-19 is adversely affecting students in Bangladesh for several significant reasons.&#x0D; Conclusion: Collective responses and analysis revealed that not technologies but also technicalities are needed to run the education system smoothly besides this pandemic situation accordingly.

Numerical study on the behaviour of vertical bolted joints for precast concrete wall-based low-rise buildings

This paper presents a numerical study on the cyclic behavior of the vertical bolted joints in low-rise precast concrete buildings. A finite element analysis model was developed for predicting the cyclic behavior of the joints which was proved with the experimental results. A step-by-step procedure was developed to carry out the finite element analysis for the contact analysis in the bolted connections. The developed approach was then applied for a parametric study to investigate the effects of main structural design factors on the joints, including the number of bolts per joint, the compressive strength of concrete, the yield strength and diameter of bolts, the thickness of blocks, the yield strength and thickness of gusset plates, the clearance of bolt as well as the arrangement of bolts in joints. Results show that the number of and the properties of steel bolts both have a significant influence on the connection performances of and the failure modes of the joints. Based on the analysis results, a smiplified model was proposed for predicting the shear capacity of the bolted joints which was expected to improve the design of proposed low-rise precast concrete buildings.