Structural Seismic Damage Assessment Method Based on Structural Dynamic Characteristics

The seismic damage state of building structure can be evaluated by observing the fundamental period change of structure. Firstly, the fundamental period calculation formula that adapts to the deformation pattern and distribution mode of horizontal seismic action for reinforced concrete frame structure is derived. Secondly, the seismic damage assessment standard of building structure considering period variation is established. Then, the seismic damage assessment method of building structure is constructed. Finally, the seismic damage example is used to verify the established evaluation method. The results show that the established research method has high accuracy and good engineering practicability.

Investigation of Dynamic Responses and Vibration Serviceability of Temporary Grandstands by a 3 DOF Interaction Model due to Swaying Motion

Excessive vibration of temporary grandstand by the crowd has lateral rhythmic motions, which attracted increasing attention in the recent years. This paper focuses on experiments where a temporary grandstand occupied by 20 participants is oscillated by a shaking table with a series of random waves and the crowd-induced rhythmic swaying motions at lateral direction, respectively. The dynamic forces that were induced by participants who have swayed at 0.5–1.8 Hz are recorded by a tri-axial human biomechanics force plate. A new relationship between the annoyance rate and structural acceleration at logarithmic coordinate is investigated and proposed, and the swaying load model is given. Based on these experimental results, a simplified three-degree-of-freedom lumped dynamic model of the joint human–structure system is reinterpreted. Afterwards, combined with a feasible range of crowd/structural dynamic parameters, a series of interaction models are analyzed, the vibration dose value (VDV) of the structure is obtained and discussed, and the notable parameters for interaction model are predicted. The experimental results show that the lateral serviceability limit is 1.29 m/s1.75 and the upper boundary is 2.32 m/s1.75. The dynamic response of model indicated that the VDV of structure will be decreased with increasing the mass of static crowd and damping ratio of the dynamic crowd. The max response of the model is α ≤ 0.6, f2 = 1.8 Hz or α > 0.6, f2 = 1.5 Hz or f1 = 2.5–3.5 Hz. It may be used as a reference value in vibration safety and serviceability assessment of TDGs, to estimate realistically the vibration response on the occasions when the crowds are swaying.

NTEGRATION OF LOGISTICS SYSTEMS OF DEVELOPING COUNTRIES INTO INTERNATIONAL LOGISTICS CHANNELS

Modern logistics significantly influences the globalization and internationalization processes. Logistics systems are becoming increasingly important in today’s rapidly changing environment. The aim of the article was to investigate the national logistics systems of developing countries in the context of their integration capabilities. The main methods used in this study are statistical analysis, index, graphical and analytical methods, methods for estimating structural dynamic shifts, comparisons. Commonly used methods of economic research, as well as statistical analysis and interstate comparisons, economic modelling (trend analysis to determine the forecast level of LPI for Ukraine), etc. were also involved. The logistics environment of Poland, Bulgaria, India and Ukraine, as well as the factors of its formation are evaluated. The components of the logistic portrait of the country in the context of integration capabilities of the logistic system are offered. It was found for the studied countries that the destimulator of the national logistics system is infrastructure (for Poland), infrastructure and customs (for Bulgaria and Ukraine), customs (for India). It is these components that need priority attention in the context of increasing the integration capabilities of logistics systems, because the results indicate that they lag far behind international standards. Prospects for further research involve studies of the impact of pandemics, globalization, digitalization on logistics systems, including that of developing countries.

Rescuing the Host Immune System by Targeting the Immune Evasion Complex ORF8-IRF3 in SARS-CoV-2 Infection with Natural Products Using Molecular Modeling Approaches

The perennial emergence of SARS-CoV-2 and its new variants causing upper respiratory complexities since December 2019 has aggravated the pandemic situation around the world. SARS-CoV-2 encodes several proteins among which ORF8 is a novel factor that is unique to SARS-CoV-2 only and is reported to help the virus in disease severity and immune evasion. ORF8-IRF3 complex induces endoplasmic reticulum stress, thus helps in the evasion of immune response. Consequently, targeting the ORF8-IRF3 complex is considered as a prime target for the discovery of novel drugs against SARS-CoV-2. In this regard, computational methods are of great interest to fast track the identification and development of novel drugs. Virtual screening of South African Natural Compounds Database (SANCDB), followed by docking and molecular dynamics (MD) simulation analysis, were performed to determine novel natural compounds. Computational molecular search and rescoring of the SANCDB database followed by induced-fit docking (IFD) protocol identified Quercetin 3-O-(6″-galloyl)-beta-D-galactopyranoside (SANC00850), Tribuloside (SANC01050), and Rutin (SANC00867) are the best scoring compounds. Structural-dynamic properties assessment revealed that these three compounds have stable dynamics, compactness, and a higher number of hydrogen bonds. For validation, we used MM/GBSA, in silico bioactivity estimation and dissociation constant (KD) approaches, which revealed that these compounds are the more potent inhibitors of the ORF8-IRF3 complex and would rescue the host immune system potentially. These compounds need further in vitro and in vivo validations to be used as therapeutics against SARS-CoV-2 to rescue the host immune system during COVID-19 infection.

Analysis of export of agricultural products in the context of the global food crisis

Purpose. The purpose of this article is to study the nature, main trends and problematic aspects of realization of the export potential of agricultural production in the countries of South America, OECD, North America and Europe in the context of aggravating food crisis. Methodology / approach. Theoretical and empirical methods of cognition are used in their dialectical combination. The main methods used in this study are statistical analysis, index, graphical and analytical methods, methods for estimating structural dynamic shifts, comparisons and monographic method. The study also involved general methods of economic research, in particular: theoretical generalization and comparison, induction and deduction are used in revealing the content of the export potential of agricultural production, drawing conclusions; the current condition and tendencies of development of export of agricultural products is estimated by means of synthesis and the economic analysis; graphic, economic, statistical and interstate comparisons are used to analyse the export of agricultural products; statistical methods (grouping) are applied to assess the domestic and external export potential of agricultural products in the regional context. The influence of external and domestic export potential on wheat exports is studied by regression analysis. Results. The need to ensure food security by countries around the world urges the importance of the agricultural sector as a catalyst for economic development, sources of foreign exchange earnings, investment direction, etc. The study of agricultural specialization led to the conclusion that wheat and sugar are goods with the highest export potential. It is substantiated that the countries of South America, OECD, North America and Europe have the highest level of fulfilment of export potential of agricultural production, and African countries are import-dependent. Besides, the low export orientation of Africa and Asia due to the peculiarities of their natural and climatic conditions is established based on the assessment of export-import operations in the regional context. The internal and external export potential of each of the regions is analysed. The direct correlation between the exports volume and area of land used for wheat cultivation, as well as with its yield, was established through the correlation and regression analysis. Originality / scientific novelty. The scientific novelty of the results of the study is that the authors were the first who carried out a comprehensive analysis of the potential capacity and ability to increase exports of agricultural products in the world and by product groups. The essence and features of economic representation of export potential of agricultural products at the international and national levels are determined. The main factors influencing the development of the export potential of agricultural products in the regional context are outlined and their influence is investigated by carrying out the regression analysis. The study of domestic and foreign export potential by regions of the world is further developed. Practical value / implications. The analysis of the internal and external export potential of agricultural production was carried out in the regional context, which resulted in the identification of the main recommendations for increasing their level in order to enhance the development of the agro-industrial sector of the economy.

One-Parameter Controlled Non-Dissipative Unconditionally Stable Explicit Structure-Dependent Integration Methods with No Overshoot

Although many families of integration methods have been successfully developed with desired numerical properties, such as second order accuracy, unconditional stability and numerical dissipation, they are generally implicit methods. Thus, an iterative procedure is often involved for each time step in conducting time integration. Many computational efforts will be consumed by implicit methods when compared to explicit methods. In general, the structure-dependent integration methods (SDIMs) are very computationally efficient for solving a general structural dynamic problem. A new family of SDIM is proposed. It exhibits the desired numerical properties of second order accuracy, unconditional stability, explicit formulation and no overshoot. The numerical properties are controlled by a single free parameter. The proposed family method generally has no adverse disadvantage of unusual overshoot in high frequency transient responses that have been found in the currently available implicit integration methods, such as the WBZ-α method, HHT-α method and generalized-α method. Although this family method has unconditional stability for the linear elastic and stiffness softening systems, it becomes conditionally stable for stiffness hardening systems. This can be controlled by a stability amplification factor and its unconditional stability is successfully extended to stiffness hardening systems. The computational efficiency of the proposed method proves that engineers can do the accurate nonlinear analysis very quickly.

A Recurrent Neural Network-Based Method for Dynamic Load Identification of Beam Structures

The determination of structural dynamic characteristics can be challenging, especially for complex cases. This can be a major impediment for dynamic load identification in many engineering applications. Hence, avoiding the need to find numerous solutions for structural dynamic characteristics can significantly simplify dynamic load identification. To achieve this, we rely on machine learning. The recent developments in machine learning have fundamentally changed the way we approach problems in numerous fields. Machine learning models can be more easily established to solve inverse problems compared to standard approaches. Here, we propose a novel method for dynamic load identification, exploiting deep learning. The proposed algorithm is a time-domain solution for beam structures based on the recurrent neural network theory and the long short-term memory. A deep learning model, which contains one bidirectional long short-term memory layer, one long short-term memory layer and two full connection layers, is constructed to identify the typical dynamic loads of a simply supported beam. The dynamic inverse model based on the proposed algorithm is then used to identify a sinusoidal, an impulsive and a random excitation. The accuracy, the robustness and the adaptability of the model are analyzed. Moreover, the effects of different architectures and hyperparameters on the identification results are evaluated. We show that the model can identify multi-points excitations well. Ultimately, the impact of the number and the position of the measuring points is discussed, and it is confirmed that the identification errors are not sensitive to the layout of the measuring points. All the presented results indicate the advantages of the proposed method, which can be beneficial for many applications.

MIGRATION MOBILITY OF THE CARPATHIAN REGION YOUTH: PROPOSITION OF IMPROVEMENT OF INFORMATION -ANALYTIC SUPPORT OF REGIONAL MIGRATION POLICY

The development of the new information-driven society along with the penetration of the globalization processes in all social and economic activities became the entities of the liberalization of the migration relations, which simplify in general the youth moving and increase its mobility. Based on statistics and administrative data analysis about youth migration from Carpathian Region it was determined that quick spreading of the positive migration aspirations among the youthful population gets new looms and can lead to the migration deprivation ramp-ups in the Carpathian Region in the future. Mainstreaming of the external migration climate and escalation of the problem are also heavily mandated by the entity of the passive state and regional migration policy, which manifests through immature system of the real complex migration registration, unfinished state of system of the institutional-organizational and institutional-legal regulation of the migration processes at the regional and local levels, low quality and low organizational and technical options of the migration services’ infrastructure elements, insufficient use of the resources of the migration exchange programs in the field of education, science, innovation and research activities, tourism, investment and business projects, the lack of regional programs of the stimulation of the educational and labor migrants’ re-emigration. In the attempt to eliminate gaps in migration policy and minimize the risks and threats of the growth of migration activity of the Carpathian Region youth, the instruments and methods of external migration monitoring system’s improvement, the development of the regional databases of migration structural-dynamic characteristics, the development of migration policy preventive instruments aimed to regulation of the regional labor markets, and the corresponding implementation of the migration services market infrastructure’s development, stimulation of the educational and labor migrants’ re-emigration, improvement of the migration policy institutional support in the Carpathian Region were proposed.

Compressor Upgrade on Existing Platform: A Study on Vibration from Structural Perspective

Due to an increase in gas lift demand on an existing field in Sarawak, an existing Gas Lift Compressor (GLC) on the processing platform requires to be upgraded to meet incremental oil production requirement. These sets of compressors consist of 2x100% reciprocating compressors that were designed for 1.5 MMscfd each, with discharge pressure of 55.1 barg (800psig). The gas from these compressors is used mainly for gas lift at the processing platform as well as gas lift, instrument gas and utility gas at adjacent wellhead platforms. From the Conceptual Study, the existing compressors are not able to be retrofit for upgrade and is to be replaced with 2 × 100 % new gas engine driven compressor that capable of delivery 3.0 MMscfd of compressed gas each. During the engineering stage of GLC package, Skid Dynamic Analysis has been carried out to evaluate the GLC skid structural design due to the operating dynamic load cases. The study recommended that the skid to be welded to the platform where the compressor is located to prevent the risk of high vibration. With the recommendation from Contractor's study, project team proceeded to carry out Structural Dynamic Analysis to assess the dynamic effect of the GLC skids to the platform deck. The Finite Element Analysis (FEA) results revealed that there are several modal modes mainly at the drilling deck and extension deck non-compliance to PTS guideline. Structural Dynamic Modification (SDM) and optimization was performed to dynamically stiffens the structures to shift the modal modes away from the operating range to fulfil PTS criteria. However, the SDM results was still unable to comply thus the need of Anti-Vibration Mounts (AVMs) is considered. Prior to application of AVMs, Structural Forced Response Analysis needs to be carried out to evaluate the risk of the system and confirm the requirement of the AVMs. Without the forced response analysis, the effect of AVMs, locations and numbers of AVMs cannot be addressed during the design study. This paper will discuss the issues concerning vibration from reciprocating compressors upgrade on an existing platform, changes in the existing operating and design philosophy, challenges in addressing compressor installation and utilization of AVM from the perspective of Project Team. The paper will also provide key lessons learn and recommendation for future considerations in Compressor upgrades on existing facilities from a Structural Engineering point of view. The project is currently at its detail design finalization and installation is expected to be completed by November 2021.