Numerical modelling of ballistic impacts on flexible protection curtains used as safety protection in woodworking

2016 ◽  
Vol 231 (1) ◽  
pp. 44-58 ◽  
Author(s):  
A Pavlovic ◽  
C Fragassa
Keyword(s):  
Numerical Simulations ◽  
Mutual Influence ◽  
Numerical Control ◽  
Work Piece ◽  
Safety Issues ◽  
Ballistic Impacts ◽  
Practical Experiences ◽  
Pass Through ◽  
The Moment ◽  
Definition Of

Numerical control boring and routing machines use curtains made from resistant, but flexible materials to protect end-users from the projection of wood chips and tool pieces. These curtains allow the work piece to gently pass through, but firmly stop every small sharp piece or fragment ejected at the highest speed by fast drilling tools. Nowadays, curtains are commonly made in flexible thermoplastic materials as polyamide, polyurethane, polyvinyl chloride or similar materials. Safety issues to be addressed related to the risk of projection of parts during processing are defined by EN 847-1 and EN 847-2 standards, both collecting practical experiences from manufacturers and users. The effectiveness of these curtains was investigated by technical observations, experiments and even numerical simulations, but conclusive results are not available at the moment. This independent research, where ballistic impacts on flexible curtains were simulated using finite element (FE) methods, aims at verifying the effectiveness of specific protective barriers when realized and used in accordance with the UNI EN 848-3 standard. Numerical simulations were permitted to verify the congruity of the main barrier’s characteristics (materials, shape, depth, mass, cost, etc.) in relation to the projectile parameters (shape, mass, speed, direction, etc.) identifying their mutual influence. Outcomes from this research provide useful information toward the definition of a new way for the design of efficient curtains. A comparison between numerical simulations and experimental results coming from ballistic tests was also realized, permitting to validate this predictive methodology.

scholarly journals Construction of a numerical model of suspension in a numerical simulation of sedimentation

2018 ◽  
Vol 46 ◽  
pp. 00011
Author(s):  
Krzysztof Kołodziejczyk
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Numerical Simulations ◽  
Particle Composition ◽  
Polydisperse Particle ◽  
Multiphase Systems ◽  
The Moment ◽  
Definition Of ◽  
Selection Of ◽  
The Way

Modeling of multiphase systems, which includes suspensions, is an issue that is continually developed. There are no procedures at the moment that would clearly determine the way in which suspension is defined in numerical simulations. The article presents an analysis of the selection of a numerical model and the definition of the suspension with a polydisperse particle composition.

The Concept “Family” in the Oral Autobiographical Stories of Siberians

2021 ◽  
pp. 39-68
Author(s):  
Svetlana V. Voloshina ◽  
◽  
Tatiana A. Demeshkina ◽  
Maria A. Tolstova ◽  
◽  
...  
Keyword(s):  
Mutual Influence ◽  
Tomsk Oblast ◽  
Moral Norms ◽  
The Family ◽  
The World ◽  
Speech Genre ◽  
Time Changes ◽  
The Moment ◽  
Definition Of ◽  
Ordinary Consciousness

The aim of the article is to analyze the implementation of the concept “family” in the speech genre of an autobiographical story. The research material is 200 oral autobiographical stories, which were recorded in the villages of Tomsk Oblast during dialectological expeditions from 1946 till 2021. The informants are residents of villages of Tomsk Oblast; they are representatives of different types of speech culture (native speakers of dialect and literary language). All stories are characterized by a relatively stable theme, means of language implementation, and structure, which allows qualifying them as a speech genre whose communicative purpose is to tell about life from the moment of birth to the moment of communication. The novelty of the article is connected with: (1) its appeal to the problem of interaction and mutual influence of the concept and the speech genre in oral everyday discourse, (2) the identification of cognitive features of the concept, (3) the definition of factors of transformation of ideas about the family in ordinary consciousness. The analysis of the concept makes it possible to obtain new data about the speech genre of the autobiographical story and its construction. The speech genre shows the dependence of the features of the content and implementation of the concept “family” on the sphere of functioning. This factor determines the theoretical significance of the results obtained. The analysis of the concept in the speech genre is carried out using the method of modeling and description of the conceptual, figurative, and value layers in the structure of the concept. As a result of contextual analysis, 16 cognitive features were identified; they are represented in the conceptual layer of the concept “family” and actualized in the speech of informants (family size, social status, compliance with moral norms, relations between family members, attitude to work, etc.). The conceptual layer is developed in detail in the oral everyday communication of Siberians. It is represented by a large number of lexical units. The figurative layer of the concept is characterized by single actualizations. At the same time, the variety of their expression is noted: metaphor, metonymy, comparisons are used. The world of the family can form the initial and resulting spheres of metaphorical models. In the initial sphere, the world of plants (roots, mushrooms), products (noodles) is mainly reflected; the semantics of unity and kinship is actualized in the initial sphere. The value layer of the concept “family” is well represented in the oral autobiographical discourse. It indicates that the family occupies one of the main places in the system of life values of peasants. The specifics of structuring this concept in the oral everyday discourse are determined mainly by the attitudes, norms of traditional culture (the family should be large, friendly, hardworking, young members of family honor the older ones, etc.). At the same time, changes in the system of family values determined by sociohistorical processes are noted. These changes are evaluated ambiguously by informants, and the family is still one of the main values of life for them. Regional (natural, social, historical, geographic) specificity is reflected in the actualization of the concept.

Dynamic behavior of a stochastic SIRS model with two viruses

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Jiandong Zhao ◽  
Tonghua Zhang ◽  
Zhixia Han
Keyword(s):  
Growth Rate ◽  
Asymptotic Stability ◽  
Global Existence ◽  
Numerical Simulations ◽  
Positive Solution ◽  
Sufficient Conditions ◽  
Environmental Noise ◽  
Sirs Model ◽  
The Moment ◽  
Disease Free

AbstractTo study the effect of environmental noise on the spread of the disease, a stochastic Susceptible, Infective, Removed and Susceptible (SIRS) model with two viruses is introduced in this paper. Sufficient conditions for global existence of positive solution and stochastically asymptotic stability of disease-free equilibrium in the model are given. Then, it is shown that the positive solution is stochastically ultimately bounded and the moment average in time of the positive solution is bounded. Our results mean that the environmental noise suppresses the growth rate of the individuals and drives the disease to extinction under certain conditions. Finally, numerical simulations are given to illustrate our main results.

Genetic manipulation on human beings

2010 ◽  
pp. 52-72
Author(s):  
Serena Zacchigna ◽  
Mauro Giacca
Keyword(s):  
Gene Therapy ◽  
Genetic Manipulation ◽  
Human Beings ◽  
Ethical Challenges ◽  
Genetic Characteristics ◽  
Safety Issues ◽  
The Public ◽  
Aesthetic Appearance ◽  
The Aesthetic ◽  
Definition Of

Since the early days of gene therapy, both the scientific community and the public have perceived the ethical challenges intrinsic to this discipline. First, the technology exploited by gene therapy is still experimental and burdened by important safety issues. Second, in several instances gene therapy aims at stably modifying the genetic characteristics of individuals. Third, the same modifications could in principle be applied also to embryos, foetuses or germ cells. Finally, while gene therapy applications are generally accepted for therapeutic purposes, the same gene transfer technologies could also be exploited to improve the aesthetic appearance, or the physical and intellectual performance of people. The definition of suitable guidelines for a controlled, ethically accepted translation of gene therapy to the clinics remains a major challenge for the near future.

The Home at the core of Modernity, an optimistic architecture

2021 ◽  
pp. 2-3
Author(s):  
Ana Tostões
Keyword(s):  
Daily Life ◽  
Single Family ◽  
The Core ◽  
The Moment ◽  
Definition Of ◽  
The Ideal ◽  
Modern Movement

Devoted to the theme of single-family houses, given the key role they played in the ideal definition of the Modern Movement architecture, as a symbolic and functional affirmation of the utopian turning of dreams into reality, the aim of this issue is to consider the transformation of daily life, and to address the architectural challenges that arose from the joy contained in what we might call the “architecture of happiness.” As we continue to endure a pandemic that has now lasted for more than a year, docomomo wishes to declare that “till the moment, the best vaccine to prevent contagion was invented by architects: the house”. Thus, in response to the question “How should we live?”, it is intended to debate the house and the home agenda as an important topic at the core of Modern Movement architecture. Nowadays, the growing emphasis on wellbeing goes beyond the seminal ideas that modern houses were “machines à habiter” and is closer to an idealistic vision of a stimulating shell for humans, which is shaped by imagination, experimentation, efficiency, and knowledge.

A Novel Incremental Sheet Bending Process of Complex Curved Steel Plate

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Qiyang Zuo ◽  
Kai He ◽  
Xiaobing Dang ◽  
Wei Feng ◽  
Ruxu Du
Keyword(s):  
Tool Path ◽  
Numerical Control ◽  
Steel Plates ◽  
Work Piece ◽  
Forming Process ◽  
Shipbuilding Industry ◽  
Supporting System ◽  
Motion Modes ◽  
Bending Process ◽  
Curved Steel

Bending complex curved steel plates for constructing ship hull has long been a challenge in shipbuilding industry. This paper presents a novel incremental bending process to obtain complicated curved steel plates by a series of sequential and layered punches. Taking advantage of this process, the blank plate that is fixed and held by a flexible supporting system can incrementally be bent into the target shape by a press tool along a planned tool path step by step and layer by layer. Acting as a “lower die,” the flexible supporting system can provide flexible and multifunctional supports for the work piece during the forming process, whose four general motion modes are demonstrated in this paper. Meanwhile, the procedures of tool path planning and forming layering are also explained in detail. In addition, aiming at different motion modes of the flexible supporting system, two springback compensation methods are given. Furthermore, according to the forming principle presented in this paper, an original incremental prototype equipment was designed and manufactured, which is mainly composed of a three-axis computer numerical control (CNC) machine, a flexible supporting system, and a three-dimensional (3D) scanning feedback system. A series of forming experiments focusing on a gradual curvature shape were carried out using this prototype to investigate the feasibility and validity of this forming process.

scholarly journals Assessment of the safety of use of portable machine tools

2018 ◽  
Vol 189 (3) ◽  
pp. 192-205
Author(s):  
Monika Nowak ◽  
Agnieszka Terelak-Tymczyna
Keyword(s):  
Machine Tool ◽  
Working Conditions ◽  
Machine Tools ◽  
Numerical Control ◽  
Milling Machine ◽  
Safety Issues ◽  
Large Size ◽  
Score Method ◽  
Characteristic Features ◽  
Risk Reducing

The article presents safety issues related to on-site machining with the use of portable machine tools. Their advantage is the possibility of machining elements at places in which they are used. This especially refers to large-size constructions, welded elements and any items whose disassembly is technically difficult. The authors present tasks performed by the operators of portable machining equipment, working conditions, construction and characteristic features of portable machine tools on the example of a portable boring machine, milling machine and flange facing machine. The presented characteristics can influence the safety of work with these machines. The information given in the article were used to asses risk at the position of a portable machine tool operator. The assessment was conducted using the Risk Score method taking into account four stages of using portable machine tools, i.e. transport, assembly/disassembly, machining and maintenance. The result of the conducted risk analysis is the proposal of possible risk reducing actions. Due to the specificity of the operation of portable machine tools which significantly impedes the development of a machine tool which would be safe in and of itself, the proposed actions refer mainly to organisational solutions. The work presents also the thesis that it is possible to decrease the risk at this position thanks to the use of numerical control in a portable machine tool. Such a solution may reduce exposure to some identified threats. The issue is presented on the example of a prototype of a portable flange facing machine developed in the Institute of Mechanical Technology ZUT in Szczecin.

scholarly journals Improvement of Accuracy of Control of Physical‑Mechanical Characteristics of Materials By Ultrasonic Pulse Method Due to Reduction of Measurement Error of Propagation Time of Elastic Waves

2018 ◽  
pp. 31-35
Author(s):  
Ya. Serikov
Keyword(s):  
Mechanical Characteristics ◽  
Pulse Method ◽  
Structural Heterogeneity ◽  
Ultrasonic Pulse ◽  
Ultrasonic Signal ◽  
Ultrasonic Transducers ◽  
Propagation Time ◽  
Information Signal ◽  
Pass Through ◽  
Definition Of

Ensuring the reliability of buildings, structures, analysis of their structural elements during reconstruction or major repair includes the task of determining the physical and mechanical characteristics of materials — strength, homogeneity, evaluation of structural heterogeneity, the presence of microcracks, etc. In solving this problem, an ultrasonic pulse method of non-destructive quality control is used. The basis of the method is the dependence of the parameters of ultrasonic oscillations, on these characteristics when they pass through the material. As the main parameter of the information ultrasonic signal, the time of its passage from the radiating to the receiving ultrasonic transducers is used. The amplitude of the information ultrasonic signal to a large extent depends on the structure of the investigated material, its acoustic resistance. At significant violations of the structure of the material there is a significant decrease in the amplitude of the information signal, which causes an increase in the error of measuring the time of its passage, and hence the definition of characteristics, quality of the investigated material. The article describes the developed method of increasing the accuracy of measuring the time of passage of the ultrasonic signal from the radiating to the receiving ultrasonic transducers. The essence of the technique is to use the mathematical modeling of the shape of the ultrasound signal, in particular the form of its so-called «first introduction».

scholarly journals Economic assessment of energy efficiency investments in dwellings = Evaluación económica de inversiones de eficiencia energética en viviendas

2017 ◽  
Vol 1 (2) ◽  
pp. 36 ◽  
Author(s):  
Hector Hernández
Keyword(s):  
Energy Efficiency ◽  
Energy Savings ◽  
Economic Assessment ◽  
Energy Performance ◽  
Point Of View ◽  
Economic Modelling ◽  
Evaluación Económica ◽  
Energy Performance Of Buildings ◽  
The Moment ◽  
Definition Of

In order to improve the energy performance of buildings, the need to value economically investments of energy efficiency associated with the rehabilitation of dwellings arises. This point of view provides an useful tool for analysts who start in the economic appraisal of energy efficiency investments. The present research gives a conceptual framework for the economic assessment of these types of investments in dwellings. As a result, it is possible to identify two techniques in the appraisals of this nature: dynamic and static approaches. Both methods contrast the benefits (energy savings) with the costs of investments over time. However, they differentiate the opportunity and the moment when investment must be carried out given an uncertainty scenario. This conceptual precision allows the study of several publications where different alternatives in retrofitting houses where evaluated, confirming the considerations that must be taken into account when economic modelling is made: the type of approach to be used (dynamic or static) and; at the definition of the investment alternatives and scenarios, the aspects of time, irrevocability and uncertainty.ResumenEn pro de la mejora del desempeño energético de los edificios, surge la necesidad de evaluar económicamente las inversiones de eficiencia energética asociadas a la rehabilitación de viviendas. Este punto de vista trata de ser una herramienta útil para analistas que se inicien en la evaluación económica de inversiones en eficiencia energética. La presente investigación muestra un marco conceptual de la evaluación económica de este tipo de inversiones en viviendas. Como resultado, es posible identificar dos enfoques presentes en los análisis económicos de esta naturaleza: el dinámico y el estático. Ambos métodos contrastan los beneficios (ahorros energéticos) con los costes de las inversiones en el tiempo. Sin embargo, diferencian la oportunidad y el momento en que la inversión debe realizarse dado un escenario de incertidumbre. Esta precisión conceptual permite estudiar varias publicaciones donde se evaluaron diferentes alternativas de reacondicionamiento en viviendas, confirmándose las consideraciones que deben tenerse presentes en momento de realizar la modelación económica: el tipo de enfoque a usar (dinámico o estático) y, en la definición de las alternativas de inversión y escenarios, los aspectos de tiempo, irrevocabilidad e incertidumbre.

scholarly journals EVALUACIÓN DE LOS RIESGOS DE AFECTACIÓN POR EL ESTABLECIMIENTO DE GRANJAS ATUNERAS EN RELACIÓN CON LA DISTRIBUCIÓN ESPACIAL DE CETÁCEOS EN EL GOLFO DULCE, COSTA RICA

2011 ◽  
Vol 1 ◽  
pp. 159 ◽  
Author(s):  
Lenin E. Oviedo Correa ◽  
Juan Diego Pacheco ◽  
David Herra Miranda
Keyword(s):  
Fish Fauna ◽  
Humpback Whales ◽  
Marine Biodiversity ◽  
Limiting Factor ◽  
Predator Population ◽  
Incidental Capture ◽  
Top Predators ◽  
Habitat Niche ◽  
Pass Through ◽  
Definition Of

Este estudio trata sobre la distribución espacial de depredadores marinos topes, particularmente cetáceos odontocetos y misticetos migratorios. Se describe el riesgo potencial de afectación por el establecimiento de instalaciones asociadas con operaciones locales de maricultura: jaulas de engorde para atún. Por medio de un enfoque teórico y empírico se establece cuantitativamente como la profundidad máxima, un factor limitante en la distribución y definición del nicho ecológico de cetáceos, se solaparía en valores con el área propuesta para el establecimiento de las jaulas, lo que induciría dos escenarios probables de afectación: el desplazamiento de las poblaciones de depredadores de un hábitat-nicho de alimentación potencial y la interacción progresiva entre los depredadores con la fauna acompañante alrededor de las instalaciones de la operación de cultivo, lo anterior implicaría un riesgo perenne de captura incidental de dichos depredadores. Adicionalmente, la presencia de ballenas jorobadas durante la temporada de lluvia en zonas aledañas a Punta Banco, se asociaría a una ruta migratoria desde las zonas de alimentación en Sudamérica-Antártica, que pasaría por el área proyectada para el establecimiento de la operación de maricultura. Los resultados ilustran la necesidad de seguir un principio precautorio y promover la reubicación de proyecto de maricultura en áreas de menor valor en términos de biodiversidad marina.This contribution deals with the spatial distribution of marine top predators, particularly odontocete and migratory misticete cetaceans. The study describes the potential risk of disturbances due to the establishment of mariculture operations and corresponding infrastructure: tuna feed lots. Through a mixed theoretical and empirical approach, this research corroborates how the maximum depth, a limiting factor in the definition of cetacean trophic niches off the study area, overlaps with the values for depths from an area proposed as the focal location of a tuna feed lot facility. The latter implies two particular scenarios: the translocation of the local predator population from a potential foraging habitat-niche, and the progressive negative interaction between predators and the accompanying fish fauna around of the cages, with a high probability of incidental capture of those predators by entanglement. Additionally, the occurrence of humpback whales during the rainy season associated with a migratory route from feeding grounds off Chile-Antarctica, that would pass through the area projected to harbor the mariculture operation. The results illustrate the need of considering a precautionary approach and relocate mariculture projects to areas of lesser value in terms of marine biodiversity.

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