stability point
Recently Published Documents


TOTAL DOCUMENTS

70
(FIVE YEARS 27)

H-INDEX

9
(FIVE YEARS 4)

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6265
Author(s):  
Mladen Zrinjski ◽  
Antonio Tupek ◽  
Đuro Barković ◽  
Ante Polović

High industrial chimney inclination monitoring and analysis is crucial from a stability point of view because, if not maintained, it can pose a great potential hazard for its surroundings. Various modern approaches of chimneys’ geometrical parameters determination have been proposed and are actively in use. However, little research regarding the applicability of the unmanned aerial system (UAS)-based photogrammetric approach of chimney structural monitoring has been conducted and a comprehensive analysis with validated methods is lacking. Therefore, this research is focused on the determination of geometrical structural parameters of a masonry chimney whereby two independent methods have been applied. Reference values of the chimney geometrical parameters have been determined by precise total station (TS) measurements and, in relation to them, the applicability of the UAS-based photogrammetric approach is evaluated. Methodologically, the reference and validation values of the chimney geometrical parameters have been determined based on double modeling of the chimney structure. Firstly, cross-sectional elliptical regression has been applied to determine the geometrical values of the chimney at predefined above-ground levels (AGLs). Secondly, the spatial chimney axis has been derived by polynomial regression to determine the inclination of the full chimney structure. Lastly, the structural stability of the chimney is validated based on its axis inclination whereby permitted deviations are determined according to the European Standard EN 1996-1-1:2005. Experimental results of our research show that consistently better results are gained by TS-based surveys and, although the determination of the chimney’s geometrical values by the UAS-based approach is certainly possible, great attention must be given to the accuracy of the UAS-generated point cloud (PC) if high accuracy results are needed.


Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1321
Author(s):  
Daniela Marian ◽  
Sorina Anamaria Ciplea ◽  
Nicolaie Lungu

In this paper, we establish some results for a Volterra–Hammerstein integral equation with modified arguments: existence and uniqueness, integral inequalities, monotony and Ulam-Hyers-Rassias stability. We emphasize that many problems from the domain of symmetry are modeled by differential and integral equations and those are approached in the stability point of view. In the literature, Fredholm, Volterra and Hammerstein integrals equations with symmetric kernels are studied. Our results can be applied as particular cases to these equations.


2021 ◽  
Vol 71 (1) ◽  
pp. 108-116
Author(s):  
Ram B. Sankar ◽  
P. K. Tiwari ◽  
B. Bandyopadhyay ◽  
H. Arya

Interceptors operate at wide range of operating conditions in terms of Mach number, altitude and angle of attack. The aerodynamic design caters for such wide operating envelope by appropriate sizing of lifting and control surfaces for meeting the normal acceleration capability requirements. The wide range of operating conditions leads to an inevitable spread in center of pressure location and hence spread in static stability. The performance of control design is a strong function of the aerodynamic static stability. The total operating envelope can be bifurcated into statically stable and unstable zones and the aerodynamic lifting surface location can be used as a control parameter to identify the neutral stability point. During the homing phase lesser static stability is desirable for good speed of response, hence the lifting surface location needs to be chosen based on the capability of control to handle instability. This paper analyses the limitations of autopilot design for the control of an unstable interceptor and brings out a method to identify the optimum aerodynamic lifting surface location for efficiently managing static margin while satisfying the control limitations and homing phase performance. This provides an input on the most appropriate lifting surface location to the aerodynamic designer during the initial CFD based aerodynamic characterisation stage itself, before commencing the rigorous wind tunnel based characterisation.


Author(s):  
Tanuj Srivastava ◽  
Pranab Sutradhar ◽  
Milan Krishna Singha Sarkar ◽  
Dipankar Narayan Basu

Supercritical natural circulation loop is a compelling technology for cooling of modern nuclear reactors, which promises enhanced thermal-hydraulic performance in a simple design. Being a new concept, related knowledge base is relatively thin and involves several conflicting theories and controversies. The chapter summarizes the observation till date, starting from the very fundamentals. The phenomenon of natural circulation under steady state condition and suitability of supercritical medium as working fluid are discussed in detail. Different methods of analyses, including analytical, simple 1-d numerical, and multidimensional computational codes, as well as experimental, are elucidated. A comprehensive discussion is presented about the effect of various geometric and operating parameters on the system behavior, from both thermal-hydraulic and stability point of view. Finally, a few recommendations are included about the operation of such loops and future direction of research.


2021 ◽  
Vol 315 ◽  
pp. 01001
Author(s):  
Elena Ananenko ◽  
Svetlana Bakhaeva

Due to the deficiency of areas for dump facilities, mining enterprises form dumps of a large height, or locate them in places unfavorable from the stability point of view. In this regard, cases of the dump areas landslides have become more frequent. Herein there are examples of the actual deformations, causes of their occurrence, as well as preventive measures. Experience of the field surveying observations and analysis of the dump landslide causes confirm that accidents could be prevented by timely substantiating of safety criteria for the stress strain status of the dumps and creating methodology for surveying monitoring, depending on a type of the overburden rock.


2020 ◽  
Author(s):  
Maria-Cristina Anicescu ◽  
Cristina-Elena Dinu-Pirvu ◽  
Mihaela Violeta Ghica ◽  
Valentina Anuta ◽  
Razvan Mihai Prisada ◽  
...  

With a long tradition in pharmaceutical design, emulsions are functional formulations that can maintain their adaptive power connected with the new formulation requirements. Hence, this study proposed preliminary assays concerning the obtaining of natural emulsions for oral administration, incorporating pumpkin seed oil and hemp seed oil as oil phases, with lecithin as emulsifying agent. Using emulsification method, O/W and W/O emulsions were prepared and characterized from a stability point of view considering organoleptic parameters, conductivity properties followed by an extensive superficial analysis by fitting two different goniometric approaches like contact angle and pendant drop models. The emulsions obtained were stable, homogeneous, their properties being reflected by composition. Conductivity values confirmed the type of emulsions, completing their profile. Superficial analysis revealed that lecithin can sustain a proper stability due to a variation of surface tension values around 25 mN/m. The mean contact angle values ranging between 31.87±0.51° and 44.01±5.48° defined an adequate wettability, being correlated with the internal structure. To conclude, this preliminary study offered important data concerning the stability of some emulsions for oral delivery, accessing natural biocompatible components. On this way, it can be created multifunctional systems with nutritional value, but also special vehicles designed for drug delivery.


2020 ◽  
Author(s):  
Laura Chirila ◽  
Alina Popescu ◽  
Sabina Olaru ◽  
Angela Danila ◽  
Rodica Roxana Constantinescu ◽  
...  

In order to obtain biomaterials with potential use in the treatment of inflammatory skin conditions, this experimental study approached the immobilization on knitted fabric, made of 100% organic cotton, of oil-in-water emulsions type, based on xanthan-propolis-cinnamon essential oil, in certain formulations. For this purpose, seven experimental variants of emulsions were prepared and characterized, by specific methods, from physical-chemical and stability point of view. The functionalized textile materials were also characterized from morphological and antibacterial activity view point. The stability index, determined after 10 days, indicated that the emulsions are stable, without showing the presence of one of the flocculation, creaming / sedimentation, coalescence or Ostwald ripening phenomena. The lowest value of the turbidity was obtained for the experimental variant containing the lowest amount of essential oil and propolis. For the same variant, the highest value of viscosity was obtained, in which 0,363 mL water /mL emulsion and 0,5 mL xanthan/mL emulsion volume fraction was used. The textile materials treated with the synthesized emulsions based on xanthan-propolis-cinnamon essential oil shows antibacterial effect against S. aureus and E. coli test strains


2020 ◽  
Vol 35 (6) ◽  
pp. 4824-4835 ◽  
Author(s):  
Hemin Golpira ◽  
Azin Atarodi ◽  
Shiva Amini ◽  
Arturo Roman Messina ◽  
Bruno Francois ◽  
...  

2020 ◽  
Vol 12 (19) ◽  
pp. 8072
Author(s):  
Bin Meng ◽  
Haibo Kuang ◽  
Erxuan Niu ◽  
Jing Li ◽  
Zhenhui Li

While promoting the global economy and trade, ports impose serious pollution on the global ocean and atmosphere. Therefore, the development of ports is restrained by the policies and measures of governments and international organizations used to cope with climate change and environmental protection. With the development of information technology, the operation and expansion of ports is facing forms of green and intelligent reform. This research aims to link the development of green intelligent ports, government policies, and third-party organizations to find the most suitable evolutionary path for the development of green intelligent ports. This paper assumes that governments will push ports to transform into green intelligent ports from the perspective of benefiting long-term interests, that the goal of ports is to maximize their profits, and that third-party organizations will actively promote the development of green intelligent ports. Based on these assumptions, this paper has established an evolutionary game theory model of “government–port–third-party organization” regarding the development of green intelligent ports. The Jacobian matrix of the game theory system was constructed by using the replicator dynamic equation, and local stability analysis was performed to obtain the equilibrium stability point of the entire system. This research reveals the limitations of the development of green intelligent ports without government involvement and explores the ability of third-party organizations to promote the implementation of policies, confirming the role of government regulation and control in promoting the development of green intelligent ports. This paper may be helpful for the development of green intelligent ports in the future. The results show that: (1) The main factors affecting the choice of port strategy are the benefits of building a green intelligent port, the intensity of government regulation, and the quantitative influence of third-party evaluation results on the port strategy selection. (2) Government decision-making plays an important role in port transformation. If the relevant government chooses the wrong strategy, then the transformation of the port will be delayed. (3) Government regulation and control need to change with the change of the evolution stage. (4) Compared with the macro-control policies of the government, the influence of the third-party organization on the port is significantly smaller.


Sign in / Sign up

Export Citation Format

Share Document