Computerized inspection of real surfaces and minimization of their deviations

A method is developed for the minimization of gear tooth surface deviations between theoretical and real surfaces for the improvement of precision of surface manufacture. Coordinate measurement machinery is used to determine a grid of surface coordinates. Theoretical calculations are made for the grid points. A least-square method is used to minimize the deviations between real and theoretical surfaces by altering the manufacturing machine-tool settings. An example is given for a hypoid gear

A Method of Effective Quarry Water Purifying Using Artificial Filtering Arrays

The development of open pit mining in the large coal basins of Russia and other countries increases their negative impact on the environment. Along with the damage of land and air pollution by dust and combustion gases of blasting, coal pits have a significant negative impact on water resources. Polluted quarry water worsens the ecological situation on a much larger area than covered by air pollution and land damage. This significantly worsens the conditions of people living in cities and towns located near the coal pits, and complicates the subsequent restoration of the environment, irreversibly destroying the nature. Therefore, the research of quarry wastewater purifying is becoming an important mater for scholars of technical colleges and universities in the regions with developing open-pit mining. This paper describes the method of determining the basic parameters of the artificial filtering arrays formed on coal pits of Kuzbass (Western Siberia, Russia), and gives recommendations on its application

Application of Face-Gear Drives in Helicopter Transmissions

The use of face gears in helicopter transmissions was explored. A light-weight, split torque transmission design utilizing face gears was described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. Analytical study of transmission error showed face-gear drives were relatively insensitive to gear misalignment, but tooth contact was affected by misalignment. A method of localizing bearing contact to compensate for misalignment was explored. The proper choice of shaft support stiffness enabled good load sharing in the split torque transmission design. Face-gear experimental studies were also included and the feasibility of face gears in high-speed, high-load applications such as helicopter transmissions was demonstrated

Face-gear drives: Design, analysis, and testing for helicopter transmission applications

The use of face-gears in helicopter transmissions was explored. A light-weight, split-torque transmission design utilizing face-gears is described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, grinding, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. An analytical study showed that the face-gear drive is relatively insensitive to gear misalignment with respect to transmission errors, but the tooth contact is affected by misalignment. A method of localizing the bearing contact to permit operation with misalignment was explored. Two new methods for grinding of the face-gear tooth surfaces were also investigated. The proper choice of shaft stiffness enabled good load sharing in the split-torque transmission design. Face-gear experimental studies were also conducted. These tests demonstrated the feasibility of face-gears in high-speed, high-load applications such as helicopter transmissions

Determination of settings of a tilted head-cutter for generation of hypoid and spiral bevel gears

Kinematics of Gleason mechanisms of hypoid and spiral bevel cutting machines are considered. These mechanisms are designated to install the position and tilt of the head cutter. The tilt of the head cutter with standard blades provides the required pressure angle. The authors have developed the matrix presentation of kinematics of these meachanisms and basic equations for the required settings. An example is presented based on the developed computation procedure

Generation of Plasmid DNA Expressing Species-Specific Horse VEGF164 and FGF2 Factors for Gene Therapy

© 2016, Springer Science+Business Media New York.In this study, we have generated a dual expression cassette plasmid DNA (pDNA) construct containing the species-specific horse (Equus caballus) codon optimized sequence encoding potent pro-angiogenic vascular endothelial growth factor (VEGF164) and basic fibroblast growth factor (FGF2) under eukaryotic promoters (EF-1α and CMV promoters, respectively). We have demonstrated effective and simultaneous recombinant proteins expression in vitro. Resulting pDNA is suitable for potential gene therapy applications in horses

Parallel and anti-parallel echoes in beam spin echo experiments

The refocusing of velocity-dependent spin-phase is the basic phenomenon behind helium and neutron spin echo beam experiments. In this paper we present quantum and classical descriptions of the spin echo phenomenon and show that non-adiabatic transitions, such as those which take place during rotation of the magnetic field axis between the two arms of a helium spin echo setup, lead to echo conditions without reversing the magnetic field orientation between the two arms. The usual spin echo conditions, created by reversing the magnetic field orientation, do not require such non-adiabatic transitions. These two echo conditions are termed parallel and anti-parallel spin echoes, respectively. We derive the dependence of the relative intensity of the two echoes on the scattering geometry of the setup and show experimental results which verify the co-existence of the two echo conditions, the theoretically derived expressions for their relative intensity and the effect of an additional spin rotator coil introduced within the non-adiabatic transition region

Disentangling trophic interactions inside a Caribbean marine reserve

Author Posting. © Ecological Society of America, 2010. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 20 (2010): 1979–1992, doi:10.1890/09-1217.1.Recent empirical studies have demonstrated that human activities such as fishing can strongly affect the natural capital and services provided by tropical seascapes. However, policies to mitigate anthropogenic impacts can also alter food web structure and interactions, regardless of whether the regulations are aimed at single or multiple species, with possible unexpected consequences for the ecosystems and their associated services. Complex community response to management interventions have been highlighted in the Caribbean, where, contrary to predictions from linear food chain models, a reduction in fishing intensity through the establishment of a marine reserve has led to greater biomass of herbivorous fish inside the reserve, despite an increased abundance of large predatory piscivores. This positive multi-trophic response, where both predators and prey benefit from protection, highlights the need to take an integrated approach that considers how numerous factors control species coexistence in both fished and unfished systems. In order to understand these complex relationships, we developed a general model to examine the trade-offs between fishing pressure and trophic control on reef fish communities, including an exploration of top-down and bottom-up effects. We then validated the general model predictions by parameterizing the model for a reef system in the Bahamas in order to tease apart the wide range of species responses to reserves in the Caribbean. Combining the development of general theory and site-specific models parameterized with field data reveals the underlying driving forces in these communities and enables us to make better predictions about possible population and community responses to different management schemes.This work was supported by funding from the Bahamas Biocomplexity Project (U.S. NSF Biocomplexity grant OCE-0119976) and U.S. EPA Science to Achieve Results (R832223)

Development of international trade of Ukraine in crisis conditions

Розраховано й проаналізовано динаміку показників міжнародної торгівлі України за період 2017–2021 рр.(зовнішньоторговельний оборот, сальдо торговельного балансу, індекс чистої торгівлі, міру залежності країни від міжнародної торгівлі, частку експорту у ВВП, частку експорту товарів та послуг у зовнішньоторговельному обороті, показники експортної, імпортної та зовнішньоторговельної квот, а також відповідних коефіцієнтів покриття). Встановлено, що незважаючи на кризові умови реалізація вітчизняного зовнішньоторговельного потенціалу за період 2017–2021 рр. покращилася, що є позитивною тенденцією. Визначено міру залежності України від міжнародної торгівлі, що свідчить про її перехід з категорії «високозалежних країн» до категорії «помірно залежних». Зазначено, що експорт України зростає швидшими темпами, ніж імпорт, а негативним чинником при цьому є висока залежність країни від імпорту (про що свідчить від’ємнє сальдо торговельного балансу протягом 2017–2020 рр.). Встановлено високий ступінь відкритості національної економіки та збільшення реалізації її експортного потенціалу, про що свідчать обсяги зовнішньоторговельної та експортної квот. Зауважено, що негативний вплив пандемії коронавірусу covid-19 на кон’юнктуру ринків у 2020 р. позначився зменшенням обсягу зовнішньоторговельного обороту. Проведено SWOT-аналіз, на основі якого обґрунтовано стратегію подальшого розвитку міжнародної торгівлі України в умовах кризи, а також надані практичні пропозиції для її реалізації. За результатами розрахунків встановлено, що слабкі сторони (недоліки) міжнародної торгівлі України переважають її сильні сторони, а рівень зовнішньоторговельної складової економічної безпеки нашої країни є від’ємним через переважання «загроз» над «можливостями» розвитку. Запропоновано задля забезпечення розвитку міжнародної торгівлі України в умовах кризи використати стратегію «міні-міні», яка спрямована на мінімізацію її «слабких» позицій та уникнення зовнішніх «загроз» розвитку. З’ясовано, що незважаючи на кризові явища, міжнародна торгівля України має великий потенціал розвитку, який вона намагається реалізовувати попри глобальні виклики та кризи.It is calculated and analyzed the dynamics of international trade indicators of Ukraine for the period 2017–2021 (foreign trade turnover, balance of trade balance, net trade index, degree of dependence of the country on international trade, share of exports in GDP, share of exports of goods and services in foreign trade turnover, indicators of export, import and foreign trade quotas, as well as corresponding coverage ratios) in the article. It was established that despite the crisis conditions, the realization of the domestic foreign trade potential for the period 2017– 2021 improved, which is a positive trend. The extent of Ukraineʼs dependence on international trade was determined, which indicates its transition from the category of «highly dependent countries» to the category of «moderately dependent countries». It is noted that Ukraineʼs exports are growing faster than imports, and the countryʼs high dependence on imports is a negative factor (as evidenced by the negative trade balance during 2017–2020). A high degree of openness of the national economy and an increase in the realization of its export potential have been established, as evidenced by the volume of foreign trade and export quotas. It was noted that the negative impact of the covid-19 coronavirus pandemic on the market situation in 2020 was affected by a decrease in the volume of foreign trade turnover. A SWOT analysis was conducted, on the basis of which the strategy for the further development of Ukraineʼs international trade in the context of the crisis was substantiated and practical proposals for its implementation were provided. Based on the results of calculations, it was established that the weaknesses (deficiencies) of Ukraineʼs international trade outweigh its strengths. And the level of the foreign trade component of our countryʼs economic security is negative due to the predominance of «threats» over «opportunities» for development. In order to ensure the development of Ukraineʼs international trade in the crisis, it is proposed to use the «mini-mini» strategy, which is aimed at minimizing its «weak» positions and avoiding external «threats» to development. It was found that despite the crisis phenomena, Ukraineʼs international trade has great development potential, which it is trying to realize despite global challenges and crises

Social media use and impact during the holiday travel planning process

Through an empirical study among holiday travellers, residing in the Former Soviet Union Republics, this paper presents a comprehensive view of role and impact of social media on the whole holiday travel planning process: Before, during and after the trip, providing insights on usage levels, scope of use, level of influence and trust. Findings suggest that social media are predominantly used after holidays for experience sharing. It is also shown that there is a strong correlation between perceived level of influence from social media and changes made in holiday plans prior to final decisions. Moreover, it is revealed that user-generated content is perceived as more trustworthy when compared to official tourism websites, travel agents and mass media advertising