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Separate flow friction formulations for laminar and turbulent regimes of flow through pipes are in common use in engineering practice. However, variation of different parameters in a system of conduits during conveying of fluids can cause changes in flow pattern from laminar to fully turbulent and vice versa. Because of that, it is useful to unify formulations for laminar and turbulent hydraulic regimes in one single coherent equation. In addition to a physical interpretation of hydraulic friction, this communication gives a short overview of already available Darcy’s flow friction formulations for both laminar and turbulent flow and additionally includes two simple completely new approximations based on symbolic regression.

This study aimed to evaluate the applicability of the Kvaal method in determining the age of a Serbian population. In this retrospective descriptive study, 170 dental patients (age range 16–77 years) were included. The measurements of six types of teeth were performed on digital orthopantomography radiographs according to the Kvaal method. Statistical inter-observer and intra-observer reliabilities were calculated to evaluate the reproducibility of the measurements, as well as to examine the correlation between chronological age and measured values. The evaluation revealed a substantial difference (over 12 years) between chronological and estimated age. The P ratio had the strongest correlation with chronological age for the maxillary central (r = ±0.293) and lateral incisors (r = ±0.240), whereas the pulp/root width ratio at level A had the strongest correlation for the mandibular first premolars (r = ±0.270). The lowest SD values, for measurements on teeth 15/25 (SD = 125,787), had the most accurate correlation with age. Thus, we can conclude that the original Kvaal method is not applicable in the age estimation of the Serbian population. For future research, we suggest using cone beam computer tomography as a precise technology to evaluate the applicability of Kvaal and other methods for age estimation.

When speaking about the total number of highly educated individuals’ migration, it is easy to spot that it is rapidly increasing. The brain drain issues should be taken very seriously especially in under developed and in the developing countries, knowing that the human capital is globally mobile and that highly educated individuals can without any issues market their knowledge around the globe. Dealing with it requires a carefully tailored strategy for these countries, which are suffering from severe human capital losses on annual basis. Since the labor markets of today are highly competitive, it is necessary for these countries to secure good advancement and doing business opportunities. The purpose of this research is to provide an insight into the key propulsive factors and potential consequences caused by the brain drain. The method used in order to conduct the research was a carefully designed questionnaire taken by the date subject enrolled at the third and fourth years of state governed and privately owned universities. This research shows that one of the key reasons for brain drain in underdeveloped and in the developing countries is shortage of further educational advancement opportunities.

The territory of the Republic of Serbia is vulnerable to various natural disasters, among which forest fires stand out. In relation with climate changes, the number of forest fires in Serbia has been increasing from year to year. Protected natural areas are especially endangered by wildfires. For Nature Park Golija, as the second largest in Serbia, with an area of 75,183 ha, and with MaB Reserve Golija-Studenica on part of its territory (53,804 ha), more attention should be paid in terms of forest fire mitigation. GIS and multi-criteria decision analysis are indispensable when it comes to spatial analysis for the purpose of natural disaster risk management. Index-based and fuzzy AHP methods were used, together with TOPSIS method for forest fire susceptibility zonation. Very high and high forest fire susceptibility zone were recorded on 26.85% (Forest Fire Susceptibility Index) and 25.75% (fuzzy AHP). The additional support for forest fire prevention is realized through an additional Internet of Thing (IoT)-based sensor network that enables the continuous collection of local meteorological and environmental data, which enables low-cost and reliable real-time fire risk assessment and detection and the improved long-term and short-term forest fire susceptibility assessment. Obtained results can be applied for adequate forest fire risk management, improvement of the monitoring, and early warning systems in the Republic of Serbia, but are also important for relevant authorities at national, regional, and local level, which will be able to coordinate and intervene in a case of emergency events.

The regulation or self-regulation of online media is one of the key dilemmas of contemporary digital media and policy environment. This includes the new digital intermediary gatekeepers such as social media. The private rules of intermediaries, such as their ‘terms of service’ and content policies, importantly define their functioning and are sometimes thought of as self-regulatory mechanisms. Online intermediaries are increasingly being called upon to engage in codes of conduct or decisions about content. We focus on Twitter as one of the largest and most relevant new gatekeepers because of its use as source of news. The terms and other documents of Twitter are analysed as tools of self-regulation, and as the context within which the individual users and mass media (must) function in today’s digital environment. We also look at how Twitter has applied this framework in two high profile cases.

In the framework of green materials, in recent years, natural fiber composites attracted great attention of academia and industry. Their mechanical and tribological characteristics, such as high strength, elasticity, friction, and wear resistance, make them suitable for a wide range of industrial applications in which issues regarding a large amount of disposal are to be considered since their environmental friendliness gives them an advantage over conventional synthetic materials. Based on the recent and relevant investigations found in the scientific literature, an overview focused on the tribological characteristics of composite materials reinforced with different types of natural fibers is presented. The aim is to introduce the reader to the issues, exploring the actual knowledge of the friction and wear characteristics of the composites under the influence of different operating parameters, as well as the chemical treatment of fibers. The main experimental tribological techniques and the main used apparatus are also discussed, with the aim of highlighting the most appropriate future research directions to achieve a complete framework on the tribological behavior of many possible natural fiber composite materials.

Background: Dental care presents affordability issues in Central & Eastern European transitional economies due to lack of insurance coverage in most countries of the region and almost complete out-of-pocket payments by citizens. Objective: Real world estimates on cost differentials across clinical dentistry branches, ICD-10 diagnostic groups and groups of dental services. Methods: Prospective case-series cost analysis was conducted from the patient perspective. A six months time horizon was adopted. Sample size was 752 complete episodes of treatment in 250 patients, selected in 2012/2013 throughout several specialist state- and private-owned dental clinics in Serbia. All direct costs of dental care were taken into account and expressed in Euros (€). Results: Mean total costs of dental care were € 46 ± 156 per single dentist visit while total costs incurred by this population sample were € 34,424. Highest unit utilization of services belongs to conservative dentistry (31.9%), oral surgery (19.5%) and radiology (17.4%), while the resource with the highest monetary value belongs to implantology € 828 ± 392, orthodontics € 706 ± 667 and prosthetics € 555 ± 244. The most frequently treated diagnosis was tooth decay (33.8% unit services provided), pulpitis (11.2%) and impacted teeth (8.5%), while most expensive to treat were anomalies of tooth position (€ 648 ± 667), abnormalities of size and form of teeth (€ 508 ± 705) and loss of teeth due to accident, extraction or local periodontal disease (€ 336 ± 339). Conclusion: Although the range of dental costs currently falls behind EU average, Serbia’s emerging economy is likely to expand in the long run while market demand for dental services will grow. Due to threatened financial sustainability of current health insurance patterns in Western Balkans, getting acquainted with true size and structure of dental care costs could essentially support informed decision making in future.

In this paper, Kaikaku method is presented. The essence of this method is introduction, principles and ways of implementation in the real systems. The main point how Kaikaku method influences on quality. It is presented on the practical example (furniture industry), one way how to implement Kaikaku method and how influence on quality improvement of production process.

This paper presents all the significant nonlinearities that exist in the description of an electro hydraulic actuator for flexible nozzle thrust vector control. Starting from practical possibilities of the theory of a nonlinear system (which are based on the analyses of one nonlinearity or one equivalent nonlinearity in the proximity of the linear description of an actuator), this paper explores the possibilities of additional analyses of a nonlinear electro hydraulic actuator for flexible nozzle thrust vector control. These explored possibilities can provide information that is useful for the design of the control algorithm, as well as for the general design of a flexible nozzle and actuator system.