Physicochemical method of fixing mobile sands with local materials

Impregnating composition with water-soluble binders has been elaborated, with the help of which the source of deflation of mobile sands is blocked, and the protective crust obtained on the sandy surface is characterized by resistance to the effects of wind-sand flow, assessed by plastic strength and thickness. The free-flow movement of a binder in a porous body of sand depends mainly on the equivalent diameter of the particles obtained by the joint solution of the internal and external problems of hydrodynamics and the shape factor of the particles. To interpret the experimental results empirically, an indicator of the saturation of the protective crust sand characterizing the impregnation as an unstable process proceeding under the predominant influence of the gravity field with an uneven movement of the liquid front was revealed. The prevalence of the elastic-plastic properties of the protective crust is evidenced by a slight and smooth change in physical and mechanical indicators over time by the third year of operation.

Stages of technological improvement of the process of continuous casting of iron-carbon and copper billets

In the article there are presented the stages of improvement of the process of continuous casting. It is revealed, that at the each stage of technological improvement of the process of continuous casting, the damage parameters of billets were reduced. Improvement of the process of continuous casting leads to the improvement of the mechanical properties of the billets and the performance of continuous casting machines. The first stage is shown as the process of transition of the number of experimental developments into quality, during which the casting of billets passed from an unstable process to a stable one. The second stage is characterized by the creation of new improved continuous casting processes. So, besides the existing machines of the vertical type, radial, curvilinear and horizontal casting machines were invented. By the end of the twentieth century, this technological process reached the limit of the possibilities for increasing the quality of performs, and the productivity of continuous casting machines. It is shown that the third stage is intended for continuous casting of copper alloys and is based on the influence of the frequency of the movement of the billets and the reverse movement of the perform during overcoming the static friction force. It was determined that for the frequency of movement of billets made of copper alloys, which are in the range of 2.5...7.5 min-1, the direction of its movement during overcoming the static friction affects the mechanical properties of the billet. The fourth stage - causes an increase in the mechanical properties of the billet due to the use of inertia forces in the alternating movement of the billet. It was revealed that at the fourth stage the mechanical properties of the billets increased most effectively, and the linear performance increased from 0.4...0.8 to 2.5...4.0 m/min, and in some cases to 5.0...7.0 m/min.

Process design for 5-axis ball end milling using a real-time capable dynamic material removal simulation

For repairing turbine blades or die and mold forms, additive manufacturing processes are commonly used to build-up new material to damaged sections. Afterwards, a subsequent re-contouring process such as 5-axis ball end milling is required to remove the excess material restoring the often complex original geometries. The process design of the re-contouring operation has to be done virtually, because the individuality of the repair cases prevents actual running-in processes. Hard-to-cut materials e.g. titanium or nickel alloys, parts prone to vibration and long tool holders complicate the repair even further. Thus, a fast and flexible material removal simulation is needed. The simulation has to predict suitable processes focusing shape deviations under consideration of process stability for arbitrary complex engagement conditions. In this paper, a dynamic multi-dexel based material removal simulation is presented, which is able to predict high-resolution surface topography and stable parameters for arbitrary processes such as 5-axis ball end milling. In contrast to other works, the simulation is able to simulate an unstable process using discrete cutting edges in real-time.

Quality Control of Building Materials According to Uncertainty of Measurement and Stability of the Technological Process of Production

Information on the influence of the state of the production process of production and the uncertainty of the measurement on the decision on the product's suitability is given. It is shown on the example of brick production that the decision to accept a batch of bricks, taking into account the measurement uncertainty under unstable condition of the production process, may be erroneous. Three variants of the state of the production process for the production of 100-grade brick are considered. The first option - the average value of compressive strength does not coincide with the middle of the tolerance field, the production process is characterized as unstable, the second option - the average value of compressive strength does not coincide with the middle of the tolerance field, a greater value of the spread of the indicators compared with the first version and is characterized as an unstable process, the third option is the average value of the tensile strength, and compression coincides with the middle of the tolerance field, is characterized as a stable and reproducible process. It is established, that, if the production process is in a state of statistical controllability, i.e. stable, then taking into account the uncertainty of measurement, the brick grade remains 100. In an unstable process with an increase in the value of the standard uncertainty of type A, the controller's decision to identify the brand of brick 100 may be erroneous. Statistically stable and reproducible process makes it possible to increase the reliability of product quality control and to avoid mistakes in deciding on the rejection of products.

DIAGNOSIS OF VENOUS ISCHEMIC STROKE. PART II (ALGORITHMS AND SEMIOLOGY OF DIAGNOSTIC RADIOLOGY. LIMITATIONS IN CLINICAL PRACTICE). A REVIEW

Venous stroke in cerebral venous sinus thrombosis is a rare pathological condition with uncertain diagnostic algorithm to ensure prompt treatment by neurologists and radiologists. All the methods are not obligatory in the workup of acute stroke, except computed tomography (CT) and transcranial Doppler. Researchers and clinicians are commonly guided by their own experiences. Therefore, the diagnosis of venous stroke is an unstable process resulting in its underestimation in the general stroke population. The optimal use of neuroimaging methods within the existing standards of care for patients with stroke, determination of the necessary and sufficient set of diagnostic procedures is an organizational and methodical problem. In addition, there is no complete description of venous ischemic stroke patterns in the medical literature. The article reviews existing evidence-based data on the diagnostic algorithms for venous stroke and discusses the probability of detecting radiologic symptoms based on the diagnostic accuracy and effectiveness of such methods as conventional CT and magnetic resonance imaging (MRI), CT and MR angiography, CT and MR perfusion, transcranial Doppler (TCD) and ultrasound of the brachiocephalic arteries stated in the national and international guidelines, as well as our own experience. Limitations of their use and options to overcome major drawbacks including the introduction of teleradiology are considered.

Magmatically folded and faulted schlieren zones formed by magma avalanching in the Sonora Pass Intrusive Suite, Sierra Nevada, California

The southwestern margin of the Late Cretaceous Sonora Pass Intrusive Suite, northern Sierra Nevada, California (USA), preserves a densely populated zone of magmatic structures that record dynamic magmatic layer formation and deformation (faulting and folding) within a solidifying upper-crustal magma mush. This zone consists largely of coupled melanocratic (or schlieren) and leucocratic bands hosted within the 95.6 ± 1.5 Ma Kinney Lakes granodiorite (Leopold, 2016), with orientations approximately parallel to the intrusive margin and with inward younging directions. Schlieren consist of a high modal abundance of medium-grained ferromagnesian minerals (hornblende + biotite), zircon, sphene, apatite, opaque minerals, and minor plagioclase and interstitial quartz. Leucocratic bands are dominated by coarse-grained feldspar + quartz with minor ferromagnesian and accessory minerals. Whole-rock geochemical and Sr and Nd isotopic data indicate that the schlieren are derived from the Kinney Lakes granodiorite by effective mechanical separation of mafic minerals and accessory phases. We interpret that the schlieren zone at the margin of the Kinney Lakes granodiorite formed by large-scale collapse of crystal mush by “magma avalanching,” facilitated by gravity, local convection, and possibly by host-rock stoping at the margin. This process eroded a significant portion of the solidifying margin of the chamber and resulted in the formation of magmatically deformed layered structures, which experienced further mingling, re-intrusion, magmatic erosion, and recycling processes. We envisage that magma avalanching of magma mushes in plutons can be achieved by any unstable process (e.g., tectonic, fluid-assisted, stoping, or gravity-driven) in large, long-lived magma-mush chambers.

A AMÉRICA LATINA: CICLO DE COMMODITIES E CRISE DO CAPITALISMO GLOBAL

This article aims to discuss the impacts of the commodity boom in Latin American economies. We will discuss the boom and its crisis within the contradictory and unstable process of globalization of capital characterized, among other things, by the hegemony of financial capital and by the spatial reconfiguration of capital accumulation, which has an enormous influence on the periphery of the system and the reorganization of the international division of labor. The paths pursued by the Latin American economies are part of this process. Thus, the analysis of the possibilities and obstacles to an inclusive economic and social development has to start from this frame of reference.

Automatic compensation of tool disturbances, caused by an unstable cutting process

Modern machining processes are characterized by a separate functioning of the elements of technological system (TS). The cutting mode, that determines the machining efficiency, depends on the functional capability of a low-performance element, and the other higher-performance elements are not able to reduce the workload of the first element. The “strong” element of the TS can not help the “weak” one in reducing the received workload. The transfer of a part of the workload from the “weak” to the “strong” element allows to use the higher cutting mode. In such statement the increase of efficiency of machining processes in the scientific and technical literature was not observed. Is offered to connect a pliable cutting tool with a rigid large-sized workpiece by special contact knot, which allows to compensate the tool perturbations, caused by unstable process of cutting. This knot provides a dissipative and elastic connection between the tool and the workpiece, has been made and tested at holes machining. As a result the increase of efficiency of machining processes of holes was installed.

ESTIMATION OF STATISTICAL CHARACTERISTICS OF THE MATHEMATICAL MODEL BY PUGACHEV'S METHOD

The article under the heading «Estimation of statistical characteristics of the mathematical model by Pugachev's method» is devoted to the problem of taking into account the error of the initial data. The essence of the problem is the need to obtain statistical estimates of probabilistic characteristics efficiently with a given accuracy, and also with minimal losses of computer time. The article consists of an introduction, two sections, an opinion, a list of references. The first section presents the current state of the investigated problem, describes methods of mathematical modeling and an algorithm for solving it. The second section is devoted to the development of a software product, describes the used tools, the structure of the software product, user classes and methods. The authors demonstrate the interface of the application and its features, as well as the results of testing, which was conducted on a set of statistical data obtained during a multifactor unstable process. The authors point out the advantages and disadvantages of Pugachev's method. Evaluating the work as a whole, it can be argued that the practical importance and prospects of the development of this direction of research is obvious.