Optimal Structural Design Under Creep Conditions

1988 ◽  
Vol 41 (12) ◽  
pp. 453-461 ◽  
Author(s):  
Michał Z˙yczkowski
Keyword(s):  
Structural Design ◽  
Elevated Temperatures ◽  
Future Research ◽  
Structural Elements ◽  
Metal Structures ◽  
Optimal Structural Design ◽  
Creep Buckling ◽  
Creep Stiffness ◽  
Plates And Shells

Optimal design of structures, or rather just of simple structural elements working under creep conditions, belongs to the most recent branches of structural optimization: It was initiated by four papers published in the years 1967–1968 (Reitman, Prager, Nemirovsky, and Z˙yczkowski). The most important differences with respect to elastic or plastic design are as follows: factor of time appearing in the constraints, a great variety of constitutive equations of creep or viscoplasticity, of creep rupture hypotheses, creep buckling theories, various definitions of creep stiffness, etc. Moreover, the constraints related to stress–relaxation are quite new. So, it is almost impossible to establish a sufficiently general theory and various types of problems must be treated separately by appropriate methods. On the other hand, the problems of optimization under creep conditions are important in view of metal structures working at elevated temperatures, structures made of plastics, concrete, etc. The paper gives classification of problems and then a review of results obtained for bars, columns, arches, trusses, frames, plates, and shells. Over 30% of those results were obtained at the Technical University of Cracow. This paper discusses specific features of the branch of optimal structural design under consideration as well as perspectives of future research.

Optimal Structural Design Under Creep Conditions

1996 ◽  
Vol 49 (9) ◽  
pp. 433-446 ◽  
Author(s):  
Michał Z˙yczkowski
Keyword(s):  
Structural Design ◽  
Elevated Temperatures ◽  
Review Article ◽  
Future Research ◽  
Metal Structures ◽  
Optimal Structural Design ◽  
University Of Technology ◽  
Creep Stiffness ◽  
Plates And Shells ◽  
Elastic Design

Optimal design of structures, or rather just of simple structural elements working under creep conditions, belongs to the most recent branches of structural optimization. It was initiated by four papers published in the years 1967-1968 (Reitman, Prager, Nemirovsky, and Z˙yczkowski). The most important differences with respect to elastic design are as follows: factor of time appearing in the constraints, a great variety of constitutive equations of creep or viscoplasticity, creep rupture hypotheses, creep buckling theories, various definitions of creep stiffness, etc. Moreover, the constraints related to stress-relaxation are quite new. So, it is almost impossible to establish a sufficiently general theory, and various types of problems must be treated separately by appropriate methods. On the other hand, the problems of optimization under creep conditions are important in view of metal structures working at elevated temperatures, structures made of plastics, concrete, etc. This review article gives a classification of problems and then a review of results obtained for bars, columns, arches, trusses, frames, plates, and shells. Over thirty percent of these results were obtained at the Cracow University of Technology. This is an extended and updated version of an earlier review article published in AMR41(12), December, 1988, discusses specific features of the branch of optimal structural design under consideration, as well as perspectives for future research. This review article contains 187 references.

DETERMINATION OF THE INFLUENCE OF STRUCTURAL ELEMENTS ON ACOUSTIC EFFICIENCY AND BACK PRESSURE IN EXHAUST AND SUCTION NOISE SILENCERS

Akustika ◽  
2021 ◽  
pp. 210-216
Author(s):  
Nickolay Ivanov ◽  
Aleksandr Shashurin ◽  
Aleksandr Burakov
Keyword(s):  
Structural Design ◽  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Back Pressure ◽  
Noise Generation ◽  
Structural Elements ◽  
The Relationship

The features of noise generation processes in exhaust and suction noise silencers are shown. A method for testing silencers has been developed. The classification of the main structural elements of exhaust and suction noise silencers, depending on the purpose, is proposed. Experimental studies of the relationship between the acoustic efficiency and the back pressure of silencers from the structural design of the elements are performed. The factors influencing the efficiency in the low-frequency and high-frequency regions of the spectrum are determined: the volume of silencers, the number of chambers, perforation, sound absorption, flow ejection, etc. Recommendations for the design of noise silencers are proposed.

Optimal Structural Design in Rheology

1971 ◽  
Vol 38 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Michal Z˙yczkowski
Keyword(s):  
Stress Relaxation ◽  
Structural Design ◽  
Critical Time ◽  
Optimal Shape ◽  
Optimal Structural Design ◽  
Time To Rupture ◽  
Creep Buckling ◽  
Constant Shape

Typical objectives of structural design and typical constraints in rheology are discussed and classified. They are divided into two groups: the objective may depend on time (creep velocities, creep displacements, stress relaxation), or may be independent of time (time to rupture, critical time in creep buckling problems). The optimal shape may be either constant in time (called here “absolute optimum”), or a function of time (temporary optimum). The latter case is of restricted engineering interest; the notion of “engineering optimum” is here introduced (constant shape, not strictly optimal). Several problems are treated in detail.

Influence of the distribution of the shear walls on the seismic response of the buildings

2020 ◽  
Vol 15 (1) ◽  
pp. 37-44
Author(s):  
El Mehdi Echebba ◽  
Hasnae Boubel ◽  
Oumnia Elmrabet ◽  
Mohamed Rougui
Keyword(s):  
Structural Analysis ◽  
Seismic Response ◽  
Natural Frequency ◽  
Structural Design ◽  
Structural Response ◽  
Shear Walls ◽  
Structural Elements ◽  
Analysis Software ◽  
Ansys Apdl ◽  
The Impact

Abstract In this paper, an evaluation was tried for the impact of structural design on structural response. Several situations are foreseen as the possibilities of changing the distribution of the structural elements (sails, columns, etc.), the width of the structure and the number of floors indicates the adapted type of bracing for a given structure by referring only to its Geometric dimensions. This was done by studying the effect of the technical design of the building on the natural frequency of the structure with the study of the influence of the distribution of the structural elements on the seismic response of the building, taking into account of the requirements of the Moroccan earthquake regulations 2000/2011 and using the ANSYS APDL and Robot Structural Analysis software.

RECLAMATION AND CULVERT CROSSINGS MADE OF CORRUGATED PIPES ON SPAWNING STREAMS

2020 ◽  
pp. 68-77
Author(s):  
O.N. CHERNYKH ◽  
◽  
A.V. RBURLACHENKO
Keyword(s):  
Single Point ◽  
Experimental Studies ◽  
Fish Passage ◽  
Future Research ◽  
Fish Stocks ◽  
Metal Structures ◽  
Natural Reproduction ◽  
Spiral Shape ◽  
Corrugated Metal ◽  
Spawning Streams

Recommendations are presented for solving issues that arise in the design and operation of tubular transport crossings of corrugated metal structures through spawning streams while ensuring the safety and natural reproduction of fish stocks. There are discussed the results of experimental studies of culverts made of metal corrugated pipes with a normal and spiral shape of corrugation the bottom of which is buried and filled with suitable granular material to the level of the natural channel of a small watercourse. It is established that when 10% of the area of the corrugated pipe is occupied by stone filling, its throughput is reduced by about 10-12%. Based on the review of the existing literature and the results of laboratory experiments, data is provided to estimate the values of the roughness coefficients of the composite cross-section of a single-point junction and directions for future research on culvert reclamation are outlined. Studying of the structure of the velocity distribution in culverts can lead to the improved conditions for fish passage without installing special structural elements in the transit path of the fish passage structure.

A Taxonomy for Psycho-Oncological Intervention Techniques in an Acute Care Hospital in Germany

2021 ◽  
pp. 1-7
Author(s):  
Martina Madl ◽  
Marietta Lieb ◽  
Katharina Schieber ◽  
Tobias Hepp ◽  
Yesim Erim
Keyword(s):  
Acute Care ◽  
Interrater Reliability ◽  
Acute Care Hospital ◽  
Future Research ◽  
Systematic Research ◽  
Care Hospital ◽  
Certification System ◽  
Stepwise Procedure ◽  
Further Development

<b><i>Background:</i></b> Due to the establishment of a nationwide certification system for cancer centers in Germany, the availability of psycho-oncological services for cancer patients has increased substantially. However, little is known about the specific intervention techniques that are applied during sessions in an acute care hospital, since a standardized taxonomy is lacking. With this study, we aimed at the investigation of psycho-oncological intervention techniques and the development of a comprehensive and structured taxonomy thereof. <b><i>Methods:</i></b> In a stepwise procedure, a team of psycho-oncologists generated a data pool of interventions and definitions that were tested in clinical practice during a pilot phase. After an adaptation of intervention techniques, interrater reliability (IRR) was attained by rating 10 previously recorded psycho-oncological sessions. A classification of interventions into superordinate categories was performed, supported by cluster analysis. <b><i>Results:</i></b> Between April and June 2017, 980 psycho-oncological sessions took place. The experts agreed on a total number of 22 intervention techniques. An IRR of 89% for 2 independent psycho-oncological raters was reached. The 22 techniques were classified into 5 superordinate categories. <b><i>Discussion/Conclusion:</i></b> We developed a comprehensive and structured taxonomy of psycho-oncological intervention techniques in an acute care hospital that provides a standardized basis for systematic research and applied care. We expect our work to be continuously subjected to further development: future research should evaluate and expand our taxonomy to other contexts and care settings.

scholarly journals Perfume and Flavor Engineering: A Chemical Engineering Perspective

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3095
Author(s):  
Alírio E. Rodrigues ◽  
Idelfonso Nogueira ◽  
Rui P.V. Faria
Keyword(s):  
Diffusion Model ◽  
Chemical Engineering ◽  
Reaction Engineering ◽  
Ternary Diagram ◽  
Future Research ◽  
Performance Parameters ◽  
Liquid Equilibrium ◽  
Research Directions ◽  
Future Research Directions

In the last two decades, scientific methodologies for the prediction of the design, performance and classification of fragrance mixtures have been developed at the Laboratory of Separation and Reaction Engineering. This review intends to give an overview of such developments. It all started with the question: what do we smell? The Perfumery Ternary Diagram enables us to determine the dominant odor for each perfume composition. Evaporation and 1D diffusion model is analyzed based on vapor-liquid equilibrium and Fick’s law for diffusion giving access to perfume performance parameters. The effect of matrix and skin is addressed and the trail of perfumes analyzed. Classification of perfumes with the perfumery radar is discussed. The methodology is extended to flavor and taste engineering. Finally, future research directions are suggested.

scholarly journals Survey of Saliva Components and Virus Sensors for Prevention of COVID-19 and Infectious Diseases

Biosensors ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 14
Author(s):  
Priya Dave ◽  
Roberto Rojas-Cessa ◽  
Ziqian Dong ◽  
Vatcharapan Umpaichitra
Keyword(s):  
Infectious Diseases ◽  
Dental Health ◽  
The United States ◽  
Human Saliva ◽  
Field Application ◽  
Future Research ◽  
Prevention Measures ◽  
Control And Prevention ◽  
Close Distance

The United States Centers for Disease Control and Prevention considers saliva contact the lead transmission mean of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes the coronavirus disease 2019 (COVID-19). Saliva droplets or aerosols expelled by sneezing, coughing, breathing, and talking may carry this virus. People in close distance may be exposed directly to these droplets or indirectly when touching the droplets that fall on surrounding surfaces and ending up contracting COVID-19 after touching the mucosa tissue of their faces. It is of great interest to quickly and effectively detect the presence of SARS-CoV-2 in an environment, but the existing methods only work in laboratory settings, to the best of our knowledge. However, it may be possible to detect the presence of saliva in the environment and proceed with prevention measures. However, detecting saliva itself has not been documented in the literature. On the other hand, many sensors that detect different organic components in saliva to monitor a person’s health and diagnose different diseases, ranging from diabetes to dental health, have been proposed and they may be used to detect the presence of saliva. This paper surveys sensors that detect organic and inorganic components of human saliva. Humidity sensors are also considered in the detection of saliva because a large portion of saliva is water. Moreover, sensors that detect infectious viruses are also included as they may also be embedded into saliva sensors for a confirmation of the presence of the virus. A classification of sensors by their working principles and the substances they detect is presented, including the sensors’ specifications, sample size, and sensitivity. Indications of which sensors are portable and suitable for field application are presented. This paper also discusses future research and challenges that must be resolved to realize practical saliva sensors. Such sensors may help minimize the spread of not only COVID-19 but also other infectious diseases.

scholarly journals Artificial Intelligence, 3D Documentation, and Rock Art—Approaching and Reflecting on the Automation of Identification and Classification of Rock Art Images

2021 ◽  
Author(s):  
Christian Horn ◽  
Oscar Ivarsson ◽  
Cecilia Lindhé ◽  
Rich Potter ◽  
Ashely Green ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Bronze Age ◽  
Data Augmentation ◽  
Rock Art ◽  
Training Data ◽  
Future Research ◽  
Rock Surface ◽  
Southern Scandinavia ◽  
Bounding Boxes

AbstractRock art carvings, which are best described as petroglyphs, were produced by removing parts of the rock surface to create a negative relief. This tradition was particularly strong during the Nordic Bronze Age (1700–550 BC) in southern Scandinavia with over 20,000 boats and thousands of humans, animals, wagons, etc. This vivid and highly engaging material provides quantitative data of high potential to understand Bronze Age social structures and ideologies. The ability to provide the technically best possible documentation and to automate identification and classification of images would help to take full advantage of the research potential of petroglyphs in southern Scandinavia and elsewhere. We, therefore, attempted to train a model that locates and classifies image objects using faster region-based convolutional neural network (Faster-RCNN) based on data produced by a novel method to improve visualizing the content of 3D documentations. A newly created layer of 3D rock art documentation provides the best data currently available and has reduced inscribed bias compared to older methods. Several models were trained based on input images annotated with bounding boxes produced with different parameters to find the best solution. The data included 4305 individual images in 408 scans of rock art sites. To enhance the models and enrich the training data, we used data augmentation and transfer learning. The successful models perform exceptionally well on boats and circles, as well as with human figures and wheels. This work was an interdisciplinary undertaking which led to important reflections about archaeology, digital humanities, and artificial intelligence. The reflections and the success represented by the trained models open novel avenues for future research on rock art.

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