Simulations of MHD Instabilities in Intracluster Medium Including Anisotropic Thermal Conduction

We perform a suite of simulations of cooling cores in clusters of galaxies in order to investigate the effect of the recently discovered heat flux buoyancy instability (HBI) on the evolution of cores. Our models follow the 3-dimensional magnetohydrodynamics (MHD) of cooling cluster cores and capture the effects of anisotropic heat conduction along the lines of magnetic field, but do not account for the cosmological setting of clusters or the presence of AGN. Our model clusters can be divided into three groups according to their final thermodynamical state: catastrophically collapsing cores, isothermal cores, and an intermediate group whose final state is determined by the initial configuration of magnetic field. Modeled cores that are reminiscent of real cluster cores show evolution towards thermal collapse on a time scale which is prolonged by a factor of ~2-10 compared with the zero-conduction cases. The principal effect of the HBI is to re-orient field lines to be perpendicular to the temperature gradient. Once the field has been wrapped up onto spherical surfaces surrounding the core, the core is insulated from further conductive heating (with the effective thermal conduction suppressed to less than 1/100th of the Spitzer value) and proceeds to collapse. We speculate that, in real clusters, the central AGN and possibly mergers play the role of "stirrers," periodically disrupting the azimuthal field structure and allowing thermal conduction to sporadically heat the core.Comment: 16 pages, 3 tables, 17 figures, accepted to ApJ with minor revisions, to appear in Volume 704, Oct 20, 2009 issu

The State and Development Prospects of Goat Production in the World

Goats are the most popular animals in the world and goat meat and milk consumption are most widely distributed in the world. Goats are popular with small holders because of their efficient conversion of feed into edible and high-quality meat, milk and hide. Goats are also used as holistic tools for land vegetation management and fire fuel load control. With proper grazing management, goats can eliminate noxious weeds, restore native grasses and prevent fires through fuel load reduction. In the world the number of goats is increasing. However, when it comes to growing goats, the conditions prevailing today are fairly complex. Problems and prospects vary by region, which consequently have different cultural and economic implications. Both global and regional approaches to livestock farming are important from the economic aspect of developed and developing nations. Rapidly increasing goat populations in developing countries point to the goat assisting in solving some of the needs created by the rising human population. Goat farming in Europe also has a more positive outlook after nearly a century of a negative reputation. Dairy-goat farming is significant to the economies of the Mediterranean countries. Dairy goats produce about 15.2 million metric tons (MT) of milk, accounting for about 2% of the world total amount of milk produced by livestock species. The developing countries produce approximately 83% of the total amount. In Europe, goat breeding is strongly oriented towards milk production, with only 3% of the world goat population producing about 15% of the world’s goat milk, which is mostly used for cheese production. Goat meat is widely consumed in the developing countries. According to FAOSTAT (2008), total meat inventory is about 280 million MT. Goat meat represents only 2% of this total. The total amount of goat meat produced in 2008 was 4.9 million MT. The developing countries produced approximately 97% of this amount, reflecting the great importance of goat meat to feed millions of people in these countries. The top ten countries producing goat meat are all from Asia and Africa. China is a world leader in producing goat meat, accounting for 38% of the world total goat meat produced. Goat meat production has been increasing from 2.65 million MT in 1990 to 4.93 million MT in 2008

Carbide Type Influence on Tribological Properties of Hard Faced Steel Layer Part II- Experimental Results

In this paper is presented a preceding procedure that should be conducted in order to successfully regenerate damaged forging dies by the hard facing process. After the tool damage types identification, as well as their causes, we have chosen the procedure and the parameters of hard facing that we further corrected by conducting the test hard facings on models. Thus, we were able to relate the experimental results outputs with the repair technology, taking as a criterion the quality of the surface layers wear resistance such as friction coefficient and width of hard faced zone, hardness and its distribution in cross section, then microstructure of characteristic of hard faced zones, etc. This research points out significancy of tribological properties of certain types of carbides and their effects on metal matrix, in which carbides are embedded. Our tribological investigations have shown that the working life of the hard faced tool can be longer than that of the new tool

Carbide Type Influence on Tribological Properties of Hard Faced Steel Layer - Part I - Theoretical Considerations

This paper gives a theoretical review of influence of the most important alloying elements on steel, and review of the most important carbide-forming elements and states the conditions which elements should fulfill in order to be considered as carbide-forming. It primarily involves alloying elements which in the iron-carbon system can form simple, complex or special carbides, i.e. phases of interstitial and substitutive type. It also gives a review of carbide types that are formed during either production or reparatory hard facing of steel parts with different types of filler materials

Пути повышения качества аудита безопасности дорожного движения в Республике Казахстан

There are two types of internationally recognized engineering approaches to addressing road safety issues – proactive and reactive. Predicted or proactive approach includes prevention of accidents and taking corrective measures before accidents can occur. One example of this approach is road safety audit, which is a relatively new tool in developing countries. The paper has analyzed approaches to road safety audit outlined in guidelines of the United Kingdom, Ireland, USA, Australia, Canada, as well as in guidelines of Asian Development Bank for the countries of Central Asian Regional Economic Cooperation. All reviewed documents are characterized by a similar approach to the basic definitions, to selection of audit team and requirements for team members, to the main stages of road safety audit. All reviewed guidelines emphasize that audit is not a means of project works evaluation, verification of compliance with standards, a means of projects ranking or evaluation. Approach to road safety audit, outlined in recommendations developed in the Republic of Kazakhstan has also been analyzed. It has been established that the document does not meet approaches adopted in developed countries. Conditions of the Republic of Kazakhstan require development of a new document based on analysis of the best international experience. Currently, the Republic of Kazakhstan has embarked on a gradual introduction of “road forgiving mistakes” approach to the design and operation of roads. This fact should also be considered when revising road safety audit manual. Существуют два типа международно признанных инженерных подходов к решению проблем безопасности дорожного движения – упреждающий и реактивный. Прогнозируемый, или упреждающий, подход включает предотвращение аварий и принятие корректирующих мер до того, как они могут произойти. Одним из примеров такого подхода является аудит безопасности дорожного движения. Это относительно новый инструмент в развивающихся странах. В статье проанализированы подходы к аудиту безопасности дорожного движения, изложенные в руководствах Великобритании, Ирландии, США, Австралии, Канады, а также в рекомендациях Азиатского банка развития для стран Центральноазиатского регионального экономического сотрудничества. Для всех рассмотренных документов характерен схожий подход к основным определениям, выбору аудиторской группы и требованиям к ее членам, основным этапам аудита безопасности дорожного движения. Во всех рассмотренных руководствах подчеркивается, что аудит – это не средство оценки работ по проекту, проверки соответствия стандартам, средство ранжирования или оценки проектов. Также был проанализирован подход к аудиту безопасности дорожного движения, изложенный в рекомендациях, разработанных в Республике Казахстан. Установлено, что документ не соответствует подходам,  принятым  в  развитых  странах.  Условия  Республики Казахстан  требуют  разработки  нового  документа, основанного на анализе лучшего международного опыта. В настоящее время Республика Казахстан приступила к постепенному внедрению концепции «прощающей ошибки дороги» в проектировании и эксплуатации дорог. Этот факт также следует учитывать при пересмотре руководства по аудиту безопасности дорожного движения